Add the Sausage, peppers, onion, garlic, salt, pepper, Italian seasoning, red chili flakes (optional), marinara sauce in a slow cooker.
Mix until combined.
Cover and cook on High heat for 3-4 hours or or on Low heat for 6-8 hours.
Remove sausages, cut them into thick slices and mix them back in the crockpot.
Garnish with parsley and enjoy!
