In a food processor, purée the warm cauliflower until smooth. Add 1 cup (100 g) of the mozzarella and 1 cup (100 g) of the cheddar. Combine until the cheese has completely melted and the mixture is smooth. Season with salt and pepper. Use a spatula to scrape down the sides of the food processor as needed. Transfer to an ovenproof dish and top with the remaining cheese.