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Vegan French Onion Tart

Vegan French Onion Tart

Creamy and so delicious, this vegan French Onion Tart has all of the texture and flavor you’d expect in a traditional quiche except it’s completely egg-free and dairy-free! Sweet, rich caramelized onions are the star, enrobed in a smooth savory custard achieved with silken tofu and cashews. The mouthwatering vegan quiche filling sits over a layer of vegan cheese, all settled into a delicate, flakey crust. Perfect for a vegan brunch in or as the meat-free main at dinner!

Thank you to Williams-Sonoma Canada for sponsoring this post. As always, all opinions are my own.

This vegan onion tart features:

  • a flakey, buttery vegan tart crust
  • an easy egg-free quiche filling made in the blender which is then combined with caramelized onions
  • a nod to classic French onion soup by deglazing the caramelized onions with beefless soup stock and by sprinkling a layer of grated dairy-free cheese onto the tart crust before pouring in the onion quiche filling and baking.
Flatlay of a quiche top in a white baking dish resting on a  wooden board, beside a mug of rose tea.

I came up with this vegan quiche recipe for Valentine’s Day this year which falls on a Sunday. Whether you celebrate it or not, who can refuse a delicious weekend vegan brunch? I used a few timeless pieces from Williams-Sonoma Canada for the brunch table. The Pillivuyt Touluse tart dish is so beautiful from oven to table. To make things extra special, I served some festive (hibiscus rose) tea in cute heart-shaped double wall latte cups. The Espro French press is great for coffee but steeps tea, too! And for some romance but so lovely for any day of the year, I used these pretty blush colored linen napkins.

How to Make a Vegan French Onion Tart

This savory vegan tart is very easy to make – the eggless quiche filling is made in the blender and the dairy-free pastry takes only minutes to mix together and roll out. You could even use store-bought vegan pastry if you’d like to simplify the recipe.

While this vegan quiche recipe is very easy, preparing the caramelized onions takes about 30-50 minutes and this is process can’t be rushed. Cooking onions nice and slow is what creates the caramelization of the onion’s natural sugars and those delicious rich flavors! You can prepare the onions up to a few days ahead of time, so the tart will take only a few minutes to prepare before baking on the day that you need it.

Vegan Pastry Tips

If you have a metal tart pan, you can roll the pastry out, fit it in your tart tin and then chill or freeze it ahead of time. If you’re like me and are using either a ceramic or glass tart or pie baking dish, chilling the pastry before rolling is best. Placing a chilled or frozen ceramic or glass baking dish into a very hot oven may crack the dish with the sudden, dramatic temperature change.

Wondering why we chill the pastry to begin with? It’s to make sure that the fat is solid before going into the oven. This way, as the vegan butter melts, it releases its moisture as steam while the pastry dough bakes up. This process helps create those delicate crisp layers of pastry. Chilling pastry before baking also helps prevent the pastry from shrinking in the pan.

9 images showing the process of making this vegan French onion tart beginning with caramelizing the onions through to what the tart looks like fresh from the oven.

How to Caramelize onions

To make caramelized onions, heat olive oil in a large skillet or heavy bottomed pot. Add the sliced onions over medium heat and cook them for about 5 minutes without stirring until you start to get some golden bits just forming on the bottom. Let the onions cook for another 3-5 minutes and then stir them again. Repeat this process until the onions have released most of their moisture and begin to turn a rich brown color. At this point, stir them every minute or two to prevent them from sticking and burning.

If the onions do start to stick, prevent them from burning by adding a splash of water to the pan. Scrape up the stuck bits with wooden spoon and lower the heat. Once they’re caramelized, deglaze with a cup of vegan beefless soup stock, scraping the bottom of the pan again to collect all those flavorful bits. Add some balsamic vinegar and thyme at this point, too, to enrich the flavor. Once the moisture has cooked off again which takes about 5 minutes, the caramelized onions are done!

A white enamel skillet filled with caramelized onions.

It’s important not to take shortcuts when preparing the caramelized onions for the vegan quiche filling for a few of reasons. The first is for flavor! Caramelized onions taste very different than sautéed onions, which is what you have if the onions have only cooked for a short time. The second reason is that the onions need to release their moisture during the caramelization process. If they don’t they will do so while baking in the tart which can result in a soggy filling. And the third reason is that the onions shrink a lot as they cook and release their juices. If the onions have not fully cooked down, there will be too much filling to fit in the tart dish . The ratio of tofu quiche filling to onions will be off so the filling won’t hold together as well.

Side view of a vegan french onion quiche in a white porcelain baking dish. In the background there is a white French press and a mug of tea.

More Vegan Brunch Ideas:

Cauliflower Gyros

Asparagus and Pesto Cashew Cheese Tart with Lemon Arugula

Leek, Asparagus and Tempeh Bacon Quiche

Brioche Cinnamon Rolls

Slice of vegan French onion tart on a white plate topped with fresh herbs.

If you make this Vegan French Onion Tart, please give it a rating in the recipe card and leave a comment below! Follow along on Instagram where you can tag me in your creations using my recipes! You can also follow me on Pinterest for vegan recipe inspiration and on Facebook. Thank you for reading!

A quiche in a white tart dish with a slice served. White vases are in the background on this brunch table.

Vegan French Onion Tart

Creamy and so delicious, this vegan French Onion Tart has all of the texture and flavor you'd expect in a traditional quiche except it's completely egg-free and dairy-free! The mouthwatering vegan quiche filling sits over a layer of vegan cheese, all settled into a delicate, flakey crust.
5 from 4 votes
Print Pin
Course: Brunch, Main
Cuisine: Vegan
Keyword: Eggless Quiche, Vegan Brunch, Vegan Caramelized Onion Quiche, Vegan Onion Quiche, Vegan Onion Recipe, Vegan Onion Tart, Vegan Quiche
Prep Time: 1 hour
Cook Time: 35 minutes
Total Time: 1 hour 35 minutes
Servings: 8
Calories: 381kcal
Author: Bronwyn

Ingredients

For the Pastry:

  • 1 cup plus 2 tbsp all-purpose flour
  • ½ tsp salt
  • ¼ tsp baking powder
  • ¼ cup vegan butter baking sticks, chilled and cubed (1/2"/1.3 cm) (not tub style vegan butter, see notes)
  • cup vegetable shortening, chilled and cubed (1/2"/1.3 cm)
  • 3-5 tbsp ice cold water

For the French Onion Tart Filling:

  • 4 tbsp extra-virgin olive oil
  • 3-4 large brown onions (8 cups/2 lbs/0.9 kg), peeled and thinly sliced root to tip
  • 2 tsp balsamic vinegar
  • 1 cup vegan "beef" soup stock
  • 1 tsp dried thyme leaves
  • 2 x 12 oz (350 g) package firm silken tofu, drained
  • cup raw cashews, soaked overnight or simmered 10 minutes and drained
  • 3 tbsp nutritional yeast
  • 1 tsp dry mustard powder (or 1 tbsp prepared mustard)
  • ½ tsp salt
  • ½ tsp ground black pepper
  • pinch ground nutmeg
  • ½ cup shredded white vegan cheese (Mozza or Monterey)

Instructions

For the Pastry:

  • In a large bowl, whisk the flour, salt and baking powder together. Add the cubes of vegan butter and shortening. Using a pastry cutter or a fork, cut the vegan butter and shortening into the flour until the fats are about the size of green peas.
  • Pour in 3 tablespoons (45 mL) of the ice water into the flour mixture, stirring with a silicone spatula or large spoon. Add more (a tablespoon at a time) water only until the dough barely holds its shape when pressed between your fingers and released. The dough should be shaggy and not sticky. If you add too much water, the pastry won't be as delicate or flaky once baked.
  • Place the pastry dough onto a lightly floured work surface. Gather and press the dough into a rough rectangle about 1/2” (1.3 cm) thick. Like you would a letter, fold the dough in thirds handling the dough as little as possible so the warmth of your hands doesn't melt the fat. Repeat this four times. With each series of folds, the dough will become more pliable. You'll see streaks of fat through the dough and this is a good thing! Wrap the dough tightly in plastic wrap and chill for an hour or up to 3 days.
  • About 30 minutes before baking, preheat the oven to 400°F/200°C/gas 6.
  • Remove the pastry from the fridge. On a lightly floured work surface, use a floured rolling pin to roll the pie dough out from the center to form a 12” (30 cm) circle for a 10” (25.4) pie dish*. As you roll, check occasionally that the dough is not sticking to the work surface, adding more flour as necessary.
  • Place the rolling pin in the middle of the pastry and fold the dough in half over the rolling pin to lift it. Lower the pastry over the pie plate, unfold the pastry. Gently lift and drape to adjust the pastry but do not force or stretch it.
  • Trim the dough if necessary so there is about 3/4” overhang. Fold the overhanging dough under the pie crust and flute or shape the edges as desired. Prick the sides and bottom of the pie crust with a fork.
  • Line the pastry with parchment paper, and fill with dried beans, pie weights or granulated sugar. Bake in the preheated oven for 12 minutes or until the bottom of the crust is just starting to brown (you'll only be able to tell if you're using a glass pie plate, otherwise just go by the timer.) Reduce the oven temperature to 325°F/165°C/gas 3.

For the Tart Filling:

  • In a large heavy bottomed pot of skillet, the olive oil over medium high heat. When the oil is shimmering, add the onions.
  • Reduce the heat to medium or medium-low. Stir the onions every 3-5 minutes to prevent sticking, but not so often that they don’t get a chance to brown. Scrape the bottom of the skillet to lift any browning to prevent burning. If the onions are browning quickly on the edges or are sticking, try turning the heat down a bit or adding a splash of water. This is a slow process which will take 30-50 minutes. Once the onions are caramelized to a rich golden brown color, stir in the soup stock, balsamic vinegar and thyme, scraping the bottom of the pot with a wooden spoon to lift any stuck bits. Turn up the heat and simmer until the moisture has evaporated. Remove the onions from the heat.
  • To a blender, add the silken tofu, soaked cashews, nutritional yeast, mustard powder, nutmeg, salt and pepper. Blend until completely smooth, scraping down the sides as necessary. This may take a few minutes depending on the how powerful your blender is.
  • In a large bowl, combine the caramelized onions and the tofu mixture, stirring well.
  • Sprinkle the vegan cheese evenly over the parbaked pastry. Pour the onion tofu filling over the cheese and smooth out the top with the back of a spoon. Place a baking dish on the bottom rack of your preheated oven and fill it with water. This will create some steam to help prevent the quiche top from splitting during baking.
  • Bake the quiche in the preheated oven for 35-40 minutes, rotating the tart in the oven once during baking for even cooking. When ready, the tart will be light brown on top and set in the middle.
  • Let the tart rest for 10 minutes before slicing and serving. Serve with fresh green salad, or as desired.
  • Store leftovers in an airtight container for up to 5 days. Reheat in the oven preheated to 350°F/177°C/gas 4. The time will vary depending on how much tart you're reheating.

Nutrition Info:

Calories: 381kcal | Carbohydrates: 24g | Protein: 8g | Fat: 29g | Saturated Fat: 6g | Trans Fat: 2g | Sodium: 528mg | Potassium: 310mg | Fiber: 3g | Sugar: 4g | Vitamin A: 64IU | Vitamin C: 3mg | Calcium: 43mg | Iron: 2mg

Notes:

This recipe was tested using a 10.5″ (26.7 cm) tart dish. Other tart or pie pans of similar sizes (e.g. 9″ is common) will work although depending on their depth, you may have extra filling. For smaller tart pans, the quiche may cook a bit faster so start checking for doneness around 30 minutes. 
 
Use only vegan butter sticks. Tub style vegan butter has a higher water content than baking sticks which can effect the quality of the pastry.
Did you make this recipe?Tag @crumbs.and.caramel on Instagram!

The Nutrition Information is only an estimate. The accuracy of the Nutrition Information for any recipe on this site cannot be guaranteed.

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