Preheat oven to 400 degrees F

Melt butter over medium heat in a saute pan. Add sliced mushrooms and cook until softened (6-8 min) Add garlic and cook for 2 more minutes, stirring constantly. Salt and pepper to taste, stir, and pour into a greased gratin dish.

Add grated cheeses on top of the mushroom and garlic mixture.

Crack eggs over the top. I wanted my yolks to be a little runny, so I cracked 6 eggs over the top and then whisked two more and poured them in the gaps that the whole eggs didn't fill in. Alternately you could whisk all the eggs and pour them over the top if you'd rather have a fluffy egg bake with a more consistent texture.

Bake 10-13 min, until eggs are cooked to your liking.