The Best Easy Stuffed Shells with Ground Beef

• 1 lb ground beef
• 2 cloves Garlic cloves
• 2 tbsp Parsley, Fresh
• 1 Yellow onion, small
• 1 Egg, large
• 2 cups Marinara sauce
• 1 cup Tomato sauce
• 12 count Pasta shells, Jumbo
• 1/4 tsp Black pepper, Freshly ground
• 1 tsp Italian seasoning
• 1/2 tsp Red pepper flakes
• 1/2 tsp Salt
• 1 cup Mozzarella
• 1/2 cup Parmesan, Grated
• 1 cup Ricotta cheese

Instructions