In a large skillet or Dutch oven, heat the olive oil over medium heat. Add the chopped onion and red bell pepper. Sauté for about 3-4 minutes, or until the vegetables become soft and the onion is translucent.
Add the ground beef and Italian sausage to the skillet. Break the meat apart with a wooden spoon and cook until browned, approximately 5-7 minutes. Drain any excess fat, if necessary.
Stir in the finely chopped pepperoni and cook for an additional 2 minutes, allowing the flavors to meld together.
Pour in the marinara sauce and crushed tomatoes. Stir to combine all the ingredients thoroughly.
Add the finely chopped hot cherry peppers, Italian seasoning, and season with salt and pepper to taste. Allow the sauce to simmer on low heat for 20-30 minutes, stirring occasionally.
While the sauce simmers, bring a large pot of salted water to a boil. Add the dry thick spaghetti and cook according to the package instructions until al dente. Drain the spaghetti in a colander.
Once the sauce has thickened and the flavors have developed, serve it over the cooked spaghetti. Garnish with freshly grated Parmesan cheese and additional chopped cherry peppers, if desired.