Preheat your oven to 375°F (190°C).
In a large skillet, over medium heat, cook the crumbled Italian sausage until browned. Drain any excess fat and stir in the pizza sauce, Italian seasoning, salt, and pepper. Remove the skillet from heat.
Slice the slider buns in half horizontally and place the bottom halves in a greased baking dish.
Spoon the sausage mixture evenly over the bun bottoms, then layer with sliced pepperoni and half of the mozzarella cheese.
Place the top halves of the buns over the cheese, pressing down gently.
In a small bowl, mix the olive oil, garlic powder, and Parmesan cheese. Brush this mixture over the tops of the buns.
Sprinkle the remaining mozzarella cheese on top of the sliders.
Cover with aluminum foil and bake for 15 minutes. Then, remove the foil and bake for an additional 5 minutes, or until the cheese is melted and bubbly.
Remove from the oven and let cool for a few minutes before slicing into individual sliders.
Garnish with fresh basil leaves if desired, and serve warm.