Preheat the oven to 375°F (190°C). Line a baking sheet with parchment paper.
Place the riced cauliflower in a microwave-safe bowl and microwave for 3–4 minutes, until soft. Let it cool, then use a clean kitchen towel or cheesecloth to squeeze out as much moisture as possible.
In a bowl, combine the cauliflower, mozzarella cheese, Parmesan cheese, egg, garlic powder, salt, and black pepper. Mix well.
Divide the mixture into four portions and press each into the base and sides of small ramekins to form a crust.
Bake for 10–12 minutes, or until slightly golden. Remove from the oven and set aside.