Preheat your oven to 375°F (190°C).
In a skillet over medium heat, cook the ground Italian sausage until browned and crumbled, about 5-7 minutes. Drain excess fat if necessary.
Add marinara sauce, pepperoni slices, and Italian seasoning to the skillet with the cooked sausage. Stir to combine and heat through for 2-3 minutes.
Cut the slider buns in half horizontally and place the bottom halves in the baking dish.
Evenly distribute the sausage mixture over the bottom halves of the slider buns.
Sprinkle mozzarella cheese on top of the sausage mixture, ensuring it covers completely.
Place the top halves of the slider buns over the cheese.
Brush the tops of the buns with olive oil and sprinkle with grated Parmesan cheese.
Cover the baking dish with aluminum foil and bake for 15 minutes.
Remove the foil and bake for an additional 5 minutes, or until the cheese is bubbly and the tops are golden brown.
Let the sliders cool for a minute, then slice and serve warm.