Easy Broccoli Quiche  2 tablespoons butter  1 onion, minced  1 teaspoon minced garlic  2 cups chopped fresh broccoli  1 (9 inch) unbaked pie crust   1 1/2 cups shredded mozzarella cheese  4 eggs, well beaten  1 1/2 cups milk  1 teaspoon salt  1/2 teaspoon black pepper  1 tablespoon butter, melted