Cheesy Meatball Sliders

Preheat oven to 350°. Combine ground beef, bread crumbs, pesto and egg; mix lightly but thoroughly. Shape into 12 meatballs; place on a greased rack in a 15x10x1-in. baking pan. Bake until browned and a thermometer reads 160°, about 35 minutes. Toss meatballs with sauce; set aside., Meanwhile, without separating rolls, cut horizontally in half; arrange bottom halves in a greased 13x9-in. baking dish. Place half the cheese slices over roll bottoms; sprinkle with oregano. Add meatballs and sauce. Top with remaining cheese slices and bun tops., Combine butter, olive oil, garlic, Italian seasoning and red pepper flakes; brush over buns. Bake, covered, for 20 minutes. Uncover; sprinkle with Parmesan and shredded mozzarella., Bake, uncovered, until cheese is melted, 10-15 minutes longer. Sprinkle with fresh basil before serving.