Coat a 9 x 13 casserole dish with nonstick cooking spray.
Arrange the bottom half of the slider buns in the casserole dish.
Place chopped chicken tenders on the buns, and then evenly the spoon marinara sauce on top of the chicken.
In a small bowl, combine mozzarella and Parmesan cheeses, and then sprinkle on top of marinara sauce.
Place the top halves of the buns on top of the sandwiches.
In a microwave-safe bowl, melt the butter in the microwave in 30-second intervals until thoroughly melted, mix in garlic powder until well combined.
Brush the sliders with melted garlic butter, and then sprinkle with Italian seasoning.
Cover with aluminum foil, and bake for 10 minutes. Remove the foil, and continue baking for another 10 minutes, or until Parmesan and mozzarella cheeses are thoroughly melted.