Set oven to 350 degrees. Place the mushrooms on a parchment lined baking sheet. Using a food processor with a S-blade, blend the olives, onion, pinenuts, half of the Parmesan cheese, garlic cloves, herbs, mustard and seasonings into a smooth mixture. Place 1 tablespoon of the mixture into each mushroom cap. Sprinkle with 1/4 tea Parmesan cheese on each, using the remainder of the cheese. Bake for 20 minutes. Serve warm.