Start by heating the olive oil over medium-high heat and adding your sliced sausage. Cook for about 5 minutes until browned. If your sausage is very fatty, drain excess grease to keep the sauce from becoming oily.
Add mushrooms and sauté for another 3 minutes. Then stir in garlic, Dijon mustard, sun-dried tomatoes, and red bell pepper, cooking for an additional 2 minutes until fragrant.
Pour in chicken broth, half-and-half, and Cajun seasoning, then add the uncooked penne. Bring to a boil, then reduce heat to medium or medium-low. Cook for about 20 minutes, stirring frequently, until the pasta is tender and the sauce has thickened.
Stir in sliced basil, season with salt and pepper, and sprinkle freshly grated parmesan on top. Serve immediately while warm for the creamiest experience.