1. Preheat oven to 425°F.
2. Place the riced cauliflower in a microwave-safe bowl and microwave for 10 minutes. Remove from the microwave and allow to fully cool for 10-20 minutes.
3. Transfer the cauliflower to a nut milk bag or clean dish cloth. If using a dish cloth, pull up on the ends and squeeze all the liquid out of the cauliflower. You should be able to squeeze out about a full cup of liquid. This is the most important step to ensuring your crust forms.
4. Transfer the cauliflower back to the bowl and add in 1/4 cup parmesan cheese, garlic powder, oregano, salt and the egg and mix well to combine.
5. On a Gefen Parchment lined baking sheet, form the cauliflower into a circlular crust shape, about 1/4 inch in thickness. Transfer the baking sheet to the preheated oven and bake until the crust is golden brown, about 20 minutes.
6. In the meantime, heat the olive oil over medium heat in a saute pan and add in the brussels sprouts, chili flakes, and pine nuts. (You can omit the chili flakes if you don’t like heat.) Cover and cook until the brussels sprouts and pine nuts have browned, about seven minutes. (Do not add salt here. The parmesan cheese is very salty and it will be over salted.)
7. Check in on the pizza crust. Once it is nice and golden brown, raise the heat on your oven to 475°F and cook for another five minutes, until the edges begin to look burnt. Depending on your oven, it may not reach the 475° temperature in that amount of time, but if the edges are browning, it’s ready.
8. Remove the crust from the oven and lower the oven to 375°F.
9. Layer the toppings over the crust. First, top with 1/4 cup with parmesan cheese, followed by all of the brussels sprouts mixture, and then a second layer of parmesan cheese.
10. Transfer the pizza back to the oven and bake until the cheese is melted, about 20 minutes.