Good-Cooking - Popover Pizza

Ingredients

• 1 pound ground beef, fried and drained
• 1/3 cup minced onion
• 1 (8 ounce) can tomato paste
• 1/2 cup water
• 1/4 teaspoon each pepper, oregano, garlic powder
• 1 (4 ounce) can mushrooms
• 1 (4 ounce) can olives
• 2 cups grated mozzarella