Prepare your stuffing ingredients : Chop the sun-dried tomatoes, the mozzarella and the olives. Chop also the garlic clove and the parsley leaves. Combine all these ingredients in a large bowl. Add grated parmesan and some pepper and mix again.
Remove the mushroom stems and wash the mushroom tops with a wet cloth. Put the mushrooms on a baking tray topped with a baking sheet.
Stuff the mushrooms with a tablespoon.
Bake for 20 minutes at 350°F (180°C). And there you are !