Step 1: 1. Preheat the oven to 190 degrees celsius and butter a large oven-proof dish. Trim mushroom stalk level with the caps.
Step 2: 2. Cream butter in a bowl and add garlic and herbs and season well.
Step 3: 3. Drop dollops of herb butter onto open side of mushrooms and place these open side up in the dish.
Step 4: 4. Cover with clingfilm and bake for 15-20 minutes.