In a large skillet set over medium-high heat, add the spicy Italian sausage. Cook until browned, breaking it apart with a spatula as it cooks. Once done, remove the sausage with a slotted spoon and transfer it to a paper towel-lined plate to drain excess fat.
Using the same pan, toss in the thinly sliced onion, green bell pepper, and sliced mushrooms. Sauté these vegetables until they soften and turn golden, which should take around five to seven minutes. Remove from heat and set aside.
Preheat your oven to 350 degrees F. While it’s warming up, lightly spray a small 9x13 jelly roll pan or casserole dish with non-stick spray, ensuring it’s evenly coated.
Now, let’s prepare the slider rolls. Take each roll and spread an even amount of marinara sauce on the bottom piece. Place the bottom halves into your prepared pan, positioning them snugly side by side.
On top of each bottom piece, add three slices of pepperoni for a classic flavor. Then, sprinkle a half cup of shredded mozzarella cheese over the pepperoni to create a delicious cheesy layer.
Next, layer the cooked sausage and the sautéed onions, peppers, and mushrooms on top of the cheese. Finish by adding more shredded mozzarella cheese to cover the top.
Take the tops of the slider buns and place them over the assembled bottoms to create complete sliders.
In a small bowl, whisk together the olive oil, garlic powder, and oregano. Brush this mixture generously over the tops of the buns, ensuring they are well coated.
Sprinkle the sliders with two tablespoons of grated Parmesan cheese for extra flavor. Bake your sliders in the preheated oven for about 20 minutes or until the tops are golden brown and the cheese is melted. Keep a close eye on them to prevent burning. If they start to brown too much, you can cover them lightly with foil.
Once baked, remove the sliders from the oven and top with the remaining grated Parmesan cheese and minced parsley. Serve warm and enjoy every cheesy, flavorful bite!
