Step 1

Heat oil in a large skillet over medium-high until just beginning to smoke. Arrange mushrooms in skillet in a single layer and cook, undisturbed, until bottom side is golden brown, about 3 minutes. Season with salt and pepper, toss mushrooms, and continue to cook, tossing often and reducing heat as needed to avoid scorching, until golden brown all over, about 5 minutes more.

Step 2

Reduce heat to medium and add butter, thyme sprigs, and garlic to skillet. Tip skillet toward you so butter pools at bottom edge. Spoon foaming butter over mushrooms until butter smells nutty, about 4 minutes. Remove mushrooms from skillet with a slotted spoon.