In a large pot or deep skillet, heat a drizzle of olive oil over medium heat. Add the sliced kielbasa and sauté until browned, about 5 minutes.
Add the diced onion and garlic to the pot, stirring to combine with the sausage. Cook for another 2-3 minutes until the onion is softened.
Stir in the bell pepper and continue cooking for another 2 minutes until slightly tender.
Add the canned tomatoes (with juices), vegetable broth, smoked paprika, oregano, and red pepper flakes. Stir to mix everything together.
Bring the mixture to a boil, then add the penne pasta. Stir well, cover the pot, and reduce the heat to a simmer. Cook for about 12-15 minutes, stirring occasionally. The pasta should be cooked al dente, and liquid mostly absorbed.
Once the pasta is cooked, stir in the shredded cheese until melted and creamy. Season with salt and pepper to taste.
Remove from heat and let it sit for a couple of minutes for the flavors to meld.
Notes
Serve garnished with fresh parsley and additional cheese if desired.