Start by boiling water in a large pot and adding a good amount of salt. Once it is bubbling, toss in the penne pasta. You want it to cook until it is al dente, which usually takes around 10 minutes. Keep tasting it to avoid overcooking.
While the pasta cooks, warm some olive oil in a large skillet over medium heat. You will know it is hot enough when it shimmers a bit. This step helps the sausage get that nice golden brown color and flavor.
Add the sliced smoked sausage to the skillet. Stir it occasionally until it is browned and starts to smell amazing. This usually takes about 5 to 7 minutes. If the pieces are overcrowded, they will steam instead of crisping up.
Toss in minced garlic, Cajun seasoning, paprika, and oregano with the sausage. You will notice a delightful aroma filling your kitchen. Cook for about a minute to release those flavors, but watch it closely to prevent burning.
Stir in the butter until it melts completely, then pour in the heavy cream. The mixture should start bubbling gently, becoming creamy and rich. Make sure to mix well so the flavors meld—burnt butter can ruin the sauce.
Drain the pasta, but save some of that water. Add the pasta straight to the skillet with the sauce. Toss everything together well, and if it feels too thick, throw in a splash of the reserved pasta water.
Sprinkle in the freshly grated Parmesan cheese and stir until everything is coated and smooth. The cheese should melt into the sauce nicely. If it clumps, just keep stirring and add a touch more cream if necessary.
Finally, plate up the pasta and add some fresh parsley on top if you like. It adds a nice pop of color and freshness. Enjoy this comforting dish hot, but watch out—it can go quickly!