Brown The Butter: Place the pieces of butter in the light-colored pan over medium heat. Once the butter melts, start to stir the butter and it will begin foam and sizzle around the edges. Keep stirring. After about 5-10 minutes, the butter will start to turn golden brown and the milk solids will sink to the bottom of the pan. It will smell buttery, butty, and rich.
Immediately add the mushrooms, garlic, thyme, rosemary, and sage. Allow to cook for about 10 minutes until the mushrooms release their liquid and it begins to disappear. Add the salt and pepper.
Serve immediately. The mushrooms stay fresh in the refrigerator for up to 5 days. Heat in the microwave for 2-3 minutes.
Make Ahead Instructions: The mushrooms can be quartered up to 3 days in advance. Store in an airtight container. Cooked mushrooms can be made up to 3 days in advance and re-heated for 2-3 minutes when ready to eat.
Butter: If using salted butter, omit the additional salt.
Spices: If you don't have fresh rosemary, sage, or thyme, you can use 1/4 teaspoon of dried of each.