Place cauliflower pieces through the feeding tube of the food processor using the grating blade; pulse until all the cauliflower is shredded.
Place a steamer insert into a saucepan and fill with water to just below the bottom of the steamer. Bring water to a boil. Add cauliflower, cover, and steam until tender, about 15 minutes. Transfer cauliflower to a large bowl and refrigerate, stirring occasionally, until cooled, about 15 minutes.
Preheat an oven to 450 degrees F (230 degrees C). Line a baking sheet with parchment paper or a silicon mat.
Stir Italian cheese blend, parsley, egg, garlic, salt, and pepper into cauliflower until evenly incorporated. Pour mixture onto the prepared baking sheet; press and shape into a pizza crust.
Bake in the preheated oven until lightly browned, about 15 minutes.