1. 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.
2. While the pasta is cooking, season the shrimp with Cajun seasoning, making sure each piece is well coated.
3. In a large skillet, heat olive oil over medium-high heat. Add the shrimp and cook for about 2-3 minutes on each side until they turn pink. Remove from the skillet and set aside.
4. In the same skillet, add butter and let it melt. Sauté the onion, garlic, and red bell pepper until the onion becomes translucent, about 5 minutes.
5. Pour in the chicken broth and heavy cream, stirring occasionally. Bring the mixture to a gentle simmer.
6. Add the Parmesan cheese gradually, stirring until the sauce thickens and becomes creamy.
7. Return the shrimp to the skillet, and add the cooked penne pasta. Toss everything together until well combined, ensuring the pasta is coated with the sauce.
8. Season with salt and pepper to taste, then garnish with freshly chopped parsley before serving.

As someone who values efficiency in the kitchen, I recommend prepping all your ingredients beforehand. It makes the process smoother and more enjoyable!