Gather all the ingredients for your Mushroom Leek Frittata, including large eggs, mushrooms, leeks, Comté cheese, cream, bacon, butter, salt, and pepper.

Preheat your oven to 350°F (180°C).

Shred the Comté cheese and set it aside.

In a mixing bowl, beat the eggs vigorously, add salt and pepper, then fold in the sautéed mushrooms, chopped leeks, cream, and cooked bacon.

In a preheated skillet, melt butter and sauté the leeks and mushrooms for about 3-4 minutes.

Pour the egg mixture over the sautéed vegetables in the skillet.

Let it cook undisturbed for roughly 2 minutes.

Transfer the skillet to the preheated oven and bake for about 15 minutes.

Optionally, sprinkle cheese on top and broil for 1-2 minutes.

Remove from oven, let cool for a few minutes before slicing, and serve warm.