Stuffed calamari

Ingredients

• 8 calamari (about 2 pounds)
• 2 tablespoons olive oil, divided
• 1 onion, finely diced
• 3 cups stale bread cubes
• 2 anchovy filets, minced
• ¼ cup chopped flatleaf parsley
• 3 tablespoons chopped black olives
• 2 tablespoons capers
• ¼ cup grated romano cheese
• 1 egg, lightly beaten
• Salt and pepper
• For the sauce
• 2 tablespoons olive oil
• 2 garlic cloves
• Pinch of chili flakes
• ¼ cup white wine
• 1 jar tomato puree (passata)
• 2 tablespoons chopped parsley for garnish