French Onion and Mushroom Tart with Gruyere Cheese 🧅🍄🧀
A buttery, golden tart packed with savory mushrooms, sweet onions, and melty cheese—perfect for any occasion!
Ingredients (Serves 8)
1¼ cups grated Gruyere cheese
1 (14-ounce) sheet puff pastry, thawed
3 tablespoons ghee or butter, divided
12 ounces shiitake or cremini mushrooms (or both), sliced
¼ cup beef stock
1 tablespoon fresh thyme leaves, divided
¼ cup sherry
Salt and black pepper, to taste
2 cloves garlic, minced
2 medium onions, halved and thinly sliced
1 egg, beaten (for egg wash)
Instructions
Caramelize Onions:
Melt 1½ tablespoons ghee in a skillet over medium heat.
Cook sliced onions with salt and pepper for about 20 minutes until golden and jammy.
Stir in sherry, reduce briefly, then add beef stock and cook down. Set aside.
Sauté Mushrooms:
In the same pan, melt the rest of the ghee over medium-high heat.
Add mushrooms, season, and cook 5–7 minutes until browned.
Stir in garlic and 1 teaspoon thyme; cook briefly. Drain on paper towels.
Prep Pastry:
Heat oven to 400°F (200°C).
Roll puff pastry to about 10×13 inches on floured parchment.
Score a ½-inch border around the edges. Prick the center with a fork.
Assemble Tart:
Sprinkle ¾ cup cheese over the pastry (inside border).
Layer mushrooms and onions on top.
Add remaining ½ cup cheese. Brush edges with egg wash.
Bake:
Bake for 26–30 minutes until pastry is deep golden.
Cool for 10 minutes, then top with remaining thyme.
Serve:
Slice into 8 pieces and enjoy warm or at room temp.