Microwave steamable cauliflower rice according to bag instructions.
While cauliflower rice cooks, to a large mixing bowl, add ground beef, shredded mozzarella, fresh parsley, egg, minced garlic, coconut aminos, Italian seasoning, onion powder, salt, and pepper. Using hands, mix together until all ingredients are well-combined. Form mixture into 12 equal-sized balls and place each on parchment paper-lined plate.
In a pan over medium-high heat, melt 2 tbsp (1 oz) butter. Add meatballs and cook 5-6 minutes on first side, then flip, and reduce stovetop heat to medium to cook for 5-6 minutes on other side. Cook until meatballs are browned and inside is cooked through. Turn stovetop heat off, transfer meatballs to clean plate, and set aside. Do not discard juices from pan.
Using a wooden spoon, scrape up any browned bits from bottom of pan. Then, in same pan over medium heat, melt remaining 2 tbsp (1 oz) butter. Add chicken stock, hot sauce, and red pepper flakes. Simmer sauce until thickened, about 2-3 minutes, stirring occasionally.
Remove steamed cauliflower rice from microwave and spoon into meal prep containers. Add 3 meatballs to each container, then drizzle sauce atop meatballs, and garnish with fresh parsley. Store in the refrigerator until ready to eat, then microwave to reheat. Season with additional salt based on taste preferences.