Baked Shells with Tomato and Mozzarella

INGREDIENTS

Olive oil

onion, diced

6 cloves

garlic, minced

Salt

1 can

good-quality whole tomatoes (I like Muir Glen), pureed in a food processor or with a stick blender*

Olive oil

1/2 cup

fresh basil leaves

3/4 lb

large shells

1/2 lb

mozzarella, diced

3/4 cup

grated parmesan cheese

Salt and pepper