Add 2 TBS of the olive oil to the bottom of the baking pan.

De-stem the mushrooms, keeping the caps in one piece, and arrange the caps in the baking pan — cap side up.

Chop the mushroom stems, and mix with the garlic, parsley, Parmesan and capers, then spoon the mixture into the mushroom caps. Cover with 2 TBS olive oil, the vinegar, salt and pepper.

Bake in a pizza-hot oven for 2-3 minutes, until the tops are brown and bubbling.