1 frozen pie crust, thawed

2 medium on-the-vine tomatoes, sliced ¼-inch thick

1 tablespoon olive oil

1 tablespoon butter

1 large yellow onion, thinly sliced

1 teaspoon fresh thyme leaves

1 clove garlic, minced

½ teaspoon salt, divided

¼ teaspoon black pepper, divided

4 large eggs

1 ¼ cups heavy cream

¼ teaspoon garlic powder

½ teaspoon Dijon mustard

1/4 teaspoon ground nutmeg

1 cup shredded Gruyère cheese (plus ¼ cup for topping)

2 tablespoons chopped fresh basil (plus extra for garnish)

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Preheat oven to 375°F. Place the pie crust in a 9-inch pie pan, prick with a fork, and line with parchment and pie weights (dry beans or rice can be substituted for the weights). Bake for 10 minutes, remove weights, and bake for 5 more minutes. Set aside.

Lower oven to 350°F. Toss tomato slices with olive oil, ¼ teaspoon salt, and a pinch of black pepper. Roast on a parchment-lined baking sheet for 20-25 minutes until slightly browned.

Melt butter in a skillet over medium heat. Add onions, ¼ teaspoon salt, and black pepper. Cook, stirring occasionally, for 20-25 minutes until golden brown. Stir in garlic and thyme for the last minute, then remove from heat.

In a bowl, whisk eggs, heavy cream, garlic powder, Dijon mustard, nutmeg, and a pinch of salt and pepper.

Sprinkle 1 cup Gruyère over the crust, layer with caramelized onions, then chopped basil, and pour the egg mixture on top. Arrange roasted tomatoes over the filling. Sprinkle the remaining ¼ cup Gruyère evenly over the top. Bake at 375°F for 40-45 minutes until set and golden. Let cool for 10 minutes.

To serve, sprinkle with fresh basil and serve warm or at room temperature.