Preheat oven to 400 degrees. Line a 9X13 pan with foil and spray with cooking spray.
Warm the meatballs in the marinara sauce in a saucepan over medium heat. Separate the dinner rolls or hot dog buns and place one saucy meatball on the bottom roll. Top with mozzarella or provolone. Place the top roll on and push down slightly. Place meatball slider in the pan and continue to assemble the rest of the sliders.
Microwave butter in a bowl in the microwave until melted. Add garlic powder and Italian seasonings and mix well. Brush tops of buns with melted butter mixture.
Toast in oven for 8-10 minutes or until toasted. I like mine a little more on the soft side...not so toasty.