Wipe the mushrooms with a damp paper towel. Cut into ¼-inch thick slices.
In a large pan, heat the olive oil and butter on medium heat. Add the mushrooms and toss with the olive oil. Then, leave the mushrooms to brown on one side without stirring for 4–5 minutes.
Add garlic and thyme. Continue cooking an additional 3–4 minutes, stirring occasionally until cooked through, golden brown, and tender.
Season with salt and pepper, and garnish with fresh thyme before serving.
Notes
Storage: Store leftovers in an airtight container in the fridge for up to 24 hours.