Make the Breadcrumb Paste: In a large bowl, mix the breadcrumbs and milk together until they form a paste. This step is the secret to moist, tender meatballs! Add the remaining ingredients, except beef, and mix well. Then add beef. Using your hands, gently mix everything until combined. Be careful not to overwork the mixture to keep the meatballs tender.

Form the Meatballs: Roll the mixture into meatballs, about 2 ½ tablespoons each. Use a light touch to avoid compacting them too tightly.

Set Up the Slow Cooker: Pour a small amount of marinara sauce into the bottom of your slow cooker to create a base layer. Arrange the meatballs on top, then pour the remaining sauce over them.

Cook Low and Slow: Cover and cook on high for 4 hours or low for 6-7 hours. The sauce will thicken slightly, and the meatballs will soak up all that saucy goodness.

Serve and Enjoy: Gently stir meatballs, then take one out and test it for doneness. Serve your meatballs with spaghetti, on sub rolls, or as part of an appetizer platter. Don’t forget a sprinkle of extra Parmesan and fresh parsley for garnish!