If you love attractive food photography, you might want to close your eyes, haha. The photos don’t do it justice, but this Caramelized Onion and Mushroom Tart is delicious.
I made this caramelized onion tart twice recently and I would happily eat it again anytime. I combined these two recipes: Rustic Onion Tart from Simply Kitchen and Onion and Mushroom Tart from The Kitchn. I wanted a tart with onion, mushroom, and ricotta, but I loved the folded crust of the first recipe. It is a bit heavy for the galette-style crust, and I can see why The Kitchn’s recipe uses a tart pan to support the mushrooms and ricotta. But it worked out fine for me, and I hope it works out for you, too!
Both times I approximated the ingredients. It’s pretty flexible in terms of the amounts of the fillings. The second tart didn’t have as many onions, but still turned out great.
There are 3 parts to the recipe:
- Onion filling
- Cheese filling
- Pastry (a pâte brisée recipe is at the bottom, or use premade pie crust)
About a pound of onions, sliced
8-12 oz of mushrooms, sliced
1 clove garlic, minced
2 TB olive oil
1 TB butter
1 tsp balsamic vinegar (optional)
Caramelizing the onions takes about 30-40 mins, so don’t heat them too high or too fast. Keep in mind that they will cook for a while. (Simply Recipes has this great tutorial on the process.)
- Heat oil and butter in pan, then add onions and sprinkle with salt.
- Cook on medium until onions are translucent, up to 10 mins.
- Then turn heat down and stir occasionally.
- After about 20 mins total in the pan, add mushrooms and garlic.
- Finish cooking (onions will be in for 30-40 min total).
- Add balsamic during the last 5 mins of cooking. (or stir in afterward if you forget)
- Take off the heat and sprinkle some thyme.
- Let this mixture cool a bit before putting into the pastry.
(When you add the mushrooms, some moisture will escape and loosen up the onions. Purists may say that this disrupts the caramelization process, but I didn’t want to dirty a separate pan to cook the mushrooms and garlic. I think it turned out fine, although it may not be technically correct. You could cook them separately and add them together at the end.)
3-4 TB ricotta cheese
3/4 to 1 cup shredded gruyère (or cheese of your choice), reserve 1/4 c for sprinkling on top
Salt and pepper
Mix together and set aside.
- Put parchment paper on baking sheet
- Roll out pastry dough to about 14 inches across
- Spread cheese in middle, leaving about 2 inches at edges
- Place onions and mushrooms on top
- Fold dough over edges of filling in sections, working your way around the tart
- Sprinkle additional cheese on top
- Bake at 450° for 10 min
- Turn down to 350° for 20-25 min until golden brown
- Let cool slightly before cutting
1 1/4 c flour (I mix all-purpose and whole wheat)
1/2 c butter (1 stick), cut into cubes
1/2 tsp salt
1/2 tsp sugar
3-5 TB ice water
Cut butter into flour, salt and sugar until mixture resembles course meal. Try to handle it as little as possible. Add water, one TB at a time until mixture will hold together. Do not add too much water. Flatten into disc and refrigerate at least 30 mins before using. Let sit for 5 mins after removing from fridge and roll out.