Melt ghee in a skillet over medium heat. Add onion and garlic; cook until tender, about 3 minutes. Stir in grated cauliflower; cook for 3 minutes more. Add asparagus and cook until tender, about 3 minutes.
Stir heavy cream, Parmesan cheese, salt, pepper, and nutmeg into the skillet; cook over medium heat until creamy, 5 to 7 minutes.