Peel and finely slice the garlic. Blend the tinned tomatoes until smooth and season with salt. Heat oil in a pan over medium heat and fry garlic for 2 mins, then add in the tomatoes and drained butter beans. Bring to a simmer and cook for 15 mins, then stir through the crème fraîche, a handful of torn basil and sherry vinegar. Taste and adjust seasoning with salt and pepper. Grate your Parmesan.
Once the beans are done, transfer to an ovenproof dish and top with torn mozzarella, grated Parm, and the rest of the basil leaves. Slide under the grill until bubbling and golden.
Allow to cool slightly and serve with a simple salad.