Meatball Sliders

Name: Meatball Sliders
Ingredients: 1 tbsp. olive oil; ½ c. finely chopped onion; 2 clove garlic; 3 slice White bread; ⅓ c. milk; ¾ lb. ground beef chuck; ½ lb. ground pork; ¼ lb. ground veal; ½ c. freshly grated Parmesan or Pecorino Romano cheese; 1 large egg; 2 tbsp. chopped fresh basil or Italian parsley; ½ tsp. Kosher salt; ½ tsp. Freshly ground black pepper; 3 c. homemade or store-bought marinara sauce; 1½ c. baby arugula; 1 package party-size potato rolls; 10 slice provolone cheese