Basil pesto makes a pretty and delicious topping for these “pizzas.”
Preheat oven to 375°F. Place the mushroom caps, gill-side up, on a rimmed baking sheet. Bake for 5 minutes. Remove from the oven and spread 1 teaspoon pesto on each mushroom. Top each cap with 1 teaspoon feta cheese, 1/4 teaspoon chopped garlic, 6 to 8 olive halves, and sprinkle with salt and pepper. Bake for 20 minutes until the mushrooms are softened and the cheese melts. Serve hot.