Preheat the oven to 375 degrees.

Melt the butter in a 10-inch oven proof skillet (preferably cast iron) over medium heat.

Add the onion and saute for 3-5 mins until golden. Add the sliced mushrooms and garlic and continue to saute until mushrooms are golden brown, about 10-12 mins.

Whisk the eggs, half and half, chives, thyme, salt and pepper together in a large bowl.

Scatter the goat cheese over the mushroom mixture and pour the egg mixture over the top.

Stir the mixture in the pan and cook over medium heat until the edges are set but the center is still loose, about 8-10 mins.

Put the pan in the oven and finish cooking for an additional 8-10 mins or until set.

Slice and serve. The frittata can be served warm or at room temperature.