Spinach Stuffed Mushrooms

Name: Spinach Stuffed Mushrooms
Prep time: 10 min
Cook time: 20 min
Total time: 10 min
Yield: 16
Cuisine: American
Ingredients: 1 tablespoon olive oil; 1/2 onion; 1 cup spinach; 2 cloves garlic; 1/2 cup cream cheese; pinch salt; pinch pepper; 16 whole mushrooms; 1/2 cup mozzarella cheese