Bring a large pot of salted water to a boil. Add the penne pasta and cook according to package instructions until al dente. Drain and set aside. If you want to save on dishes, you can skip this step and cook the pasta directly in the skillet later, just add extra broth.
Heat the olive oil in a large skillet over medium-high heat. Add the thinly sliced beef sirloin in a single layer. Cook for about 2-3 minutes per side until browned and cooked through. Remove the beef from the skillet and set aside.
In the same skillet, add the sliced green bell pepper and onion. Sauté for 5-7 minutes until softened and slightly caramelized. Add the minced garlic and cook for another 30 seconds until fragrant.
Pour the beef broth into the skillet with the veggies. Stir in the Italian seasoning, salt, and pepper. Let the mixture simmer for 3-4 minutes to reduce slightly and concentrate the flavors.
Add the cooked pasta and the beef back into the skillet. Toss everything together until combined and heated through. Sprinkle the shredded provolone and cheddar cheeses over the top, stirring gently until melted and creamy.
Once the cheese has melted and coated the pasta, remove from heat. Serve immediately, garnished with extra pepper or fresh herbs if desired. This dish pairs beautifully with a fresh green salad or a side of roasted veggies.