Preheat the Oven to 375°F (190°C). Slice slider buns in half horizontally and place the bottom halves in a baking dish.
Dip chicken slices into the egg, then coat with breadcrumbs. Fry in a pan until crispy and cooked through.
Spread a spoonful of marinara sauce on the bottom half of each bun. Place a piece of chicken on each bun. Spoon more marinara over the chicken. Sprinkle mozzarella and Parmesan cheeses over the top. Place the bun tops on.
Mix melted butter, minced garlic, and Italian seasoning in a small bowl.
Brush the butter mixture over the tops of the sliders. Cover with foil and bake for 10 minutes. Remove the foil and bake an additional 5-7 minutes, until the cheese melts and the tops are golden.
Let cool slightly. Garnish with fresh basil if desired. Enjoy warm!