I developed this Gluten Free French Onion Soup Tart recipe for my first gluten-free cookbook, "Beyond Flour: A Fresh Approach to Gluten-Free Cooking and Baking".
I wanted to do a caramelized onion tart in general, but soon decided that I'd base all the flavours around French onion soup. I liked the idea of including a custard base, as one would normally do for *dessert* tarts .. but a savoury custard, picking up more of the flavours of French Onion soup.
Everything came together so well! Don't be intimidated by the long ingredient list - it's a little bit of work, but it's not especially difficult work. This Gluten Free French Onion Soup Tart is worth the effort - it makes an impressive offering for any brunch,dinner, or get together.

Also, if you're interested in gluten-free cooking and baking, you should definitely check out my gluten-free cookbooks: Beyond Flour: A Fresh Approach to Gluten Free Cooking & Baking, and the sequel... Beyond Flour 2. You can order them right here on my website, through Amazon, or through any major bookseller.
Looking for More Pie Recipes?
Pies, tarts... good stuff put into a flaky crust. I've got you!
Note: All recipes designated as gluten-free can alternately be made "regular" - just swap in your favourite pie crust recipe or store bought crust!
Creamy Blueberry Amaretto Pie
Maple Butter Tarts
Partridgeberry Pie
Savoury Alligator Pie
Southern Comfort Peach Pie
Strawberry Grand Marnier Chiffon Pie
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Gluten Free French Onion Soup Tart
Equipment
Ingredients
Crust:
- 1 cup Shredded Gruyere cheese
- ¾ cup Light buckwheat flour
- ½ cup White rice flour
- ¼ cup Sweet rice flour
- 1 Tbsp Tapioca starch
- ¼ cup Corn starch
- 1 tsp Xanthan gum
- ½ tsp Salt
- ½ tsp Baking powder
- 1 Large egg
- ½ cup Lard
- ¼ cup Cold water
Caramelized Onions
- ½ cup Butter
- 3 lbs Sweet onions peeled and sliced
- ½ cup Dry white wine
- ½ tsp Salt
- 2 tsp Granulated sugar
- ½ cup Beef stock
- 1 tsp Chopped fresh thyme
- Salt and pepper
Custard Filling
- 2 Tbsp Butter
- 2 Garlic cloves pressed or minced
- ¼ cup Dry white wine
- ½ cup Beef broth
- 5 Large egg yolks
- 1 Tbsp Corn starch
- ¾ cup Milk
- 1 cup Shredded Gruyere cheese
- Salt and pepper
Instructions
Crust:
- Measure cheese, flours, starches, xanthan gum, salt, and baking powder into the bowl of your food processor, blitz to combine.
- Add egg and lard to the bowl, blitz a few times until mixture resembles gravel.
- Stream in cold water as you run the food processor, just long enough to bring it together as a dough.
- Remove dough from processor, knead lightly to bring it together as a ball. Wrap in plastic film, chill for 1 hour.
- Preheat oven to 350 F (180 C).
- Generously dust work surface with corn starch, Roll chilled dough out to a rough circle that's slightly bigger than 12" in diameter.
- Carefully transfer rolled dough to tart pan, smoothing the bottom and pressing the dough into the sides of the pan. Trim any excess dough that extends past the top of the pan, prick the flat (bottom) surface of the crust a few times with a fork.
- Bake for 25-30 minutes or until golden brown. While tart is baking, prepare your caramelized onions.
Caramelized Onions:
- In a large pot over medium-high heat, cook onions in butter until they start to soften.
- Add wine and salt, continue cooking - stirring often - until nicely brown.
- Add sugar and beef stock to pan, stir well, and continue cooking until onions are nicely caramelized.
- Remove from heat, stir in fresh thyme, season with salt and pepper to taste.
Custard Filling
- In a small saucepan, melt butter over medium heat. Add garlic, white wine, and beef broth, once again whisking until smooth. Gently bring mixture up to a simmer.
- While wine mixture is heating up, whisk egg yolks and corn starch together in a small bowl or measuring glass. once smooth, whisk in milk - a little at a time - until smooth and well incorporated.
- Once the wine mix has come to a simmer, add milk mixture, quickly whisking to fully blend the two. Bring up to a simmer again, whisking constantly. As it heats up, add the Gruyere cheese, stirring to melt and combine.
- Once custard has thickened to your liking, remove from heat, season with salt and pepper to taste
For serving hot:
- Spread hot custard in warm crust, top with hot caramelized onions, serve immediately.
For a cold tart:
- Allow everything to cool to room temperature before spreading custard in crust and topping with onions. Chill until serving.
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