Pre heat oven to 350 degrees and line a baking tray with aluminum foil (spray with non stick cooking spray)
Microwave your riced cauliflower for around four minutes
Mix egg, a handful of spinach and parm cheese into the cauliflower
Dump mixture onto baking sheet and mush around with hands into desired crust shape. I got creative and went with a "circle". I know, wild and crazy me! Keep the crust under half an inch. This made about an 8" pie.
Bake for 12 minutes
Pull from oven and put about two tablespoons of marinara sauce on the crust, which should be lightly springy and a golden brown. Layer cheese and veggies in desired arrangement.
Pop back into oven and cook for about 5 more minutes
Eat it before anyone comes home and tries to steal a slice.