Mix turkey, pesto, panko, Parmesan, salt, and pepper until just combined.
Roll mixture into 2-inch meatballs and place on a plate.
Microwave meatballs on high for 5 minutes to render fat.
In the slow cooker, combine crushed tomatoes, tomato paste, onion, garlic, Italian seasoning, red pepper flakes, sugar, and salt.
Transfer microwaved meatballs to the slow cooker, discarding rendered fat.
Gently stir to coat meatballs in sauce.
Cover and cook on low for 4 to 5 hours until meatballs are tender.
Serve over cooked pasta and garnish with fresh basil or parsley.