How to Make It
Preheat oven to 500°F. Line a rimmed baking sheet with foil.
Coat mushrooms with cooking spray; place, top sides down, on prepared pan. Top with 1/2 teaspoon pepper. Bake at 500°F for 4 minutes.
Combine 6 tablespoons panko and oil in a small bowl. Combine remaining 6 tablespoons panko, chives, rind, juice, salt, and goat cheese in a bowl. Spoon 1/4 cup goat cheese mixture into each mushroom; top with panko mixture. Bake at 500°F for 3 minutes. Top with prosciutto and remaining 1/4 teaspoon pepper.