Parmesan Cauliflower Rice Skillet

riced cauliflower (about 1 medium head)

white onion, chopped

large cloves garlic, minced

fresh Parmesan, finely grated

tablespoons vegetable stock

Juice of one lemon (+ zest, if you like)

Red chili pepper flakes, optional

unsalted butter divided

fresh parsley, chopped