In a large, heavy-bottomed pot, heat the olive oil over medium heat until shimmering.
Add the sliced kielbasa to the pot, frying until browned and slightly crispy, about 5-7 minutes.
Incorporate the finely diced onion, minced garlic, and thinly sliced red bell pepper into the pot. Sauté for another 3-4 minutes until the onion is translucent.
Introduce the diced zucchini to the mix, stirring well to combine all the ingredients.
Carefully pour in the chicken broth and bring the mixture to a gentle simmer.
Add the penne pasta, dried Italian seasoning, red pepper flakes, and season generously with salt and freshly cracked pepper.
Cover the pot and let it cook for 10-12 minutes, or until the pasta is al dente.
Once the pasta is cooked to your liking, fold in the halved cherry tomatoes and chopped spinach. Cook for an additional 2-3 minutes.
Remove the pot from heat, and stir in the finely grated Parmesan cheese until it melts and combines with the other ingredients.
Taste the pasta and adjust the seasoning if necessary.
Serve the dish hot, garnished with fresh basil leaves.
Notes
Serve in deep bowls and consider a light drizzle of olive oil and extra Parmesan for garnish.