Stromboli Grinder

Preheat oven to 500 degrees F (260 degrees C).

Place marinara sauce in a small saucepan over medium-low heat; cook until warmed through, about 5 minutes. Reduce heat to low and keep warm until sandwiches are ready.

Heat olive oil in a large skillet over medium-high heat; cook and stir onion, red bell pepper, jalapeno pepper, and goat horn pepper in the hot oil until onion softens and begins to turn golden, 7 to 8 minutes. Remove onion mixture to a plate and set aside.

Place salami and pepperoni in the hot skillet and cook until crisp, about 2 minutes per side.

Spread each hoagie bun with 1/4 cup mascarpone cheese and 1 tablespoon garlic spread. Top each roll with 4 slices salami and 4 slices pepperoni. Sprinkle with onion mixture and mozzarella cheese.

Place sandwiches onto a baking sheet and bake in the preheated oven until cheese is melted and bread is toasted, about 5 minutes. Spoon 1/2 cup warm marinara sauce over each sandwich.