First, roast the tomatoes. Preheat the oven to 175 C / 340 F.
Place your tomatoes on an oven tray with the whole garlic cloves, drizzle with olive oil and season with salt and pepper.
Roast for 30-45 minutes and drain off any excess water that comes out of the tomatoes. We want them almost caramelised, and too much juice will saturate the dish.
Blend the tomatoes and garlic together to make a smooth sauce.
Now cook your gnocchi for two minutes or according to the packet
Spoon half the gnocchi into an ovenproof dish and top with half of the sauce. Gently mix them together, before topping with half the mozzarella and half the parmesan. Repeat the process until the dish is filled and parmesan covers the entire top.
Bake in the oven for 15 minutes, and for the final two minutes turn on the grill to crisp up the top and leave the cheese browned and bubbling.