Sauté onion and garlic in olive oil until soft, about 4 minutes.
Add canned tomatoes, chili flakes, Italian seasoning, salt and pepper, making sure to mash the tomatoes with a potato masher or wooden spoon.
Add white beans.
Cook until sauce thickens and flavors meld together, about 20 minutes.
Sprinkle with mozzarella cheese, olives, and giardiniera.
Bake at 400°F/204°C oven until bubbling and cheese is melted, about 10 minutes.
Garnish with Parmesan, basil, and parsley.
Serve with bread and enjoy!
