Tender and flavorful meatballs with an incredible homemade marinara sauce made in the slow cooker. Add the meatballs and sauce to a slider roll, add cheese, and broil them to make the ultimate meatballsliders. These sliders are the perfect hearty meal or appetizer and are sure to please a crowd.
In a large bowl, combine the beef, sausage meat, bread crumbs, Parmesan, eggs, grated onion, garlic, herbs, salt, and pepper. Mix well. Form the mixture into balls, about 2 tablespoons per meatball. (A small ice cream scooper works well here.)
Heat the olive oil in a large heavy-bottomed pot over medium-high heat. When the oil shimmers, add the meatballs in a single layer. You don't want to crowd the pan or the meatballs won't brown, so you may need to work in batches. Brown the meatballs on all sides, 5 to 7 minutes per side. Take your time here, they don't cook through a ton more in the crockpot. Transfer the meatballs to a paper towel-lined plate and repeat with the remaining meatballs.
Make the sauce
Combine all of the sauce ingredients in a 6-quart slow cooker (or see Note 1) and stir to combine. Add the meatballs, stirring gently to coat with the sauce. Cover and cook on low for 6 hours or on high for 3 hours, until the meatballs are cooked through. Remove and discard the bay leaves. Taste and season with addition salt and pepper, if necessary.
To serve, place cooked noodles in a dish or bowl, top with marinara sauce and meatballs, and sprinkle with freshly grated parmesan cheese and basil if desired. Serve hot.