Preheat the Oven: Start by preheating your oven to 375°F (190°C) so it’s hot and ready for the sliders.
Make the Meatballs: In a large bowl, combine the ground beef or turkey with breadcrumbs, Parmesan cheese, garlic powder, onion powder, Italian seasoning, salt, pepper, and the beaten egg. Mix until just combined.
Form the Meatballs: Roll the mixture into meatballs, making them about 1-1.5 inches in diameter. Place them on a lined baking sheet.
Bake the Meatballs: Bake the meatballs in the preheated oven for 20–25 minutes or until cooked through and browned.
Add the Marinara Sauce: Once the meatballs are ready, pour the marinara sauce over them, ensuring they are well coated.
Prepare the Buns: Cut the slider buns in half and place the bottom halves in a baking dish. Lay a meatball on each bun and sprinkle with mozzarella cheese.
Melt the Cheese: Top with the bun tops and return to the oven for another 5 minutes or until the cheese is melted and bubbly.
Serve: Garnish with fresh basil if desired, then serve warm with extra marinara sauce on the side for dipping.