Introduction

This French Onion Mushroom Tart is an elegant combination of deeply caramelized onions, earthy mushrooms, and creamy Gruyere cheese nestled in a flaky tart crust. Perfect for brunch, a light dinner, or entertaining guests, it’s a dish that’s as visually stunning as it is flavorful.

Ingredients
Tart Crust:

1 tart crust (store-bought or homemade)

Filling:

3 large onions, thinly sliced

2 tablespoons olive oil

2 tablespoons butter

1 teaspoon sugar

1 teaspoon salt

½ teaspoon black pepper

1 pound mushrooms, sliced

2 cloves garlic, minced

1 tablespoon fresh thyme, chopped (or 1 teaspoon dried thyme)

1 cup grated Gruyere cheese

Custard:

½ cup heavy cream

2 eggs

Instructions
1. Preheat Oven