Preheat the oven to 425 degrees F.
Pulse the cauliflower florets in a food processor to a fine snowy powder. Transfer the processed cauliflower to a microwave-safe bowl and cover. Microwave until soft, 4 to 6 minutes. Transfer to a clean, dry kitchen towel and allow to cool.
When cool enough to handle, wrap the cauliflower in the towel and wring out as much moisture as possible, transferring to a second towel if necessary.
In a large bowl, stir together the cauliflower, Parmesan, Italian seasoning, salt, egg and 1/2 cup of the mozzarella until well combined.
Line a rimmed baking sheet with parchment paper and spray the parchment with cooking spray. Use a 1 3/4-inch cookie scoop to scoop out a heaped amount of the mixture onto the parchment. Flatten with a cup into a thin 4-inch disc. Repeat with the remaining mixture to make 6 mini pizza crusts. Bake until golden, 15 minutes.
Remove the crusts from the oven and top with some of the Creamy Tomato Sauce--not too much--and the remaining 1/2 cup mozzarella. Return to the oven and bake until the cheese is melted and bubbly, 5 minutes more.
Garnish with the cherry tomatoes and fresh basil leaves just before serving.
Put the butter and olive oil in a saucepan over medium heat. Add the garlic and onions and saute until soft, about 8 minutes. Add the tomato puree, heavy cream, salt, red pepper flakes and black pepper and cook for 10 minutes.