In a medium pan, brown ground beef until no pink remains. Add onion and red pepper cook 3-5 more minutes until veggies soften.
Stir in garlic, oregano, basil, parsley, bay leaf, salt, red pepper flakes and black pepper, Cook and stir 1 minute.
Stir in diced tomatoes, crushed tomatoes, tomato paste, broth, and sugar. Pour into 4-6 quart slow cooker.
Cover and cook on low for 6-7 hours (stirring once half way through if possible).
Stir, remove bay leaf and serve with parmesan cheese if desired.
Notes
I always, always make a huge batch of spaghetti sauce and freeze it in smaller portions so it's easy to grab, thaw and heat for a quick meal! It works best to chill the sauce in the fridge before filling a Ziploc freezer bag or plastic freezer-friendly containters. Seal tightly and freeze.