Preheat your oven to 350 degrees Fahrenheit.
In a skillet, heat olive oil over medium heat.
Add chopped onions, garlic, and bell peppers.
Sauté until they are soft and fragrant.
In a large bowl, combine ground beef, Italian sausage, eggs, breadcrumbs, Parmesan cheese, basil, parsley, salt, and black pepper.
Add the sautéed vegetables to the meat mixture.
Mix everything well.
Transfer the mixture into a loaf pan, pressing it down evenly.
Smooth the top with a spatula.
Bake in the oven for 1 hour or until the internal temperature reaches 160 degrees Fahrenheit.
Let it rest for a few minutes before slicing to serve.