Baked Shells

Ingredients

• olive oil
• Kosher salt, fresh ground black pepper
• large or 4 small onions , diced
• garlic, thinly sliced, plus 1 clove garlic, grated
• 1 teaspoon crushed red pepper flakes, optional
• can whole peeled tomatoes, packed in juice
• can crushed tomatoes
• ricotta
• tablespoons heavy cream
• pound large pasta shells
• pound salted mozzarella, roughly torn by hand or grated on a box grater
• Parmesan, for grating