To prepare a clam stuffed mushroom caps appetizers recipe, first you will need to gather your ingredients. First, you'll need the following ingredients: 2 tablespoons butter, 1 teaspoon kosher salt, 1/2 teaspoon pepper, and 2 teaspoons thyme. You will also need 1 tablespoon olive oil, 1/4 cup chopped chives, 2 tbsp. dried dill weed, 4 sprigs of fresh rosemary and 1/8 teaspoon each salt and pepper. Mix all of the ingredients together with your hands until the mixture is evenly coated. If you don't want to use feta cheese, skip this step and use parmesan cheese instead.