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French Onion Mushroom Tart

A savory tart made with caramelized onions, sautéed mushrooms, Gruyère cheese, and a flaky pastry crust.
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Prep Time 30 minutes
Cook Time 45 minutes
Total Time 1 hour 15 minutes
Servings: 6 slices
Course: Dessert, Snack
Cuisine: American, Autumn
Calories: 320

Ingredients
  

Crust
  • 1.25 cups all-purpose flour
  • 0.5 tsp salt
  • 0.5 cup unsalted butter cold, cubed
  • 3-4 tbsp ice water
Filling
  • 2 tbsp olive oil
  • 2 tbsp unsalted butter
  • 3 yellow onions thinly sliced
  • 8 oz mushrooms sliced
  • 1 tsp fresh thyme
  • 0.75 cup Gruyère cheese shredded
  • 0.5 cup heavy cream
  • 2 eggs large

Equipment

  • Mixing bowls
  • Skillet
  • Tart pan
  • Oven

Method
 

  1. Prepare tart dough and chill for 30 minutes.
  2. Caramelize onions slowly in butter and olive oil until golden.
  3. Sauté mushrooms until browned; add garlic and thyme.
  4. Whisk eggs, cream, and cheese together.
  5. Assemble tart with onions, mushrooms, and egg mixture.
  6. Bake at 375°F (190°C) for 35–40 minutes.
  7. Cool slightly before slicing and serving.

Notes

Let onions caramelize slowly for best flavor.