Begin by ricing your cauliflower. If using fresh, cut into florets and pulse in a food processor until rice-like. If frozen, thaw and drain excess moisture.
Place riced cauliflower in a clean kitchen towel or cheesecloth. Squeeze out as much moisture as possible.
In a large mixing bowl, combine riced cauliflower, egg, cheddar cheese, Parmesan cheese, flour, grated onion, garlic, salt, and pepper. Mix until well incorporated.
Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper. Shape small portions of the mixture into tots and place on the baking sheet.
Bake for about 20-25 minutes, flipping halfway through, until golden brown and crispy.
Remove from oven and let cool slightly before serving. Enjoy with your favorite dipping sauce!