Bring a large pot of salted water to a rolling boil.
Place the salmon chunks in a large bowl and season with Cajun seasoning on all sides.
Heat some oil in a large skillet over medium-high heat. Cook the salmon for 2-3 minutes on each side, be careful not to overcook the salmon. Squeeze 1/2 of a lemon over the salmon chunks.
Remove the salmon from the skillet and set it aside. Add the butter, garlic, and red crushed pepper to the skillet and cook until fragrant.
Add the heavy cream, half and half, and parmesan cheese. Cook for 12-15 minutes while whisking frequently. If you notice that the sauce is starting to separate, continue whisking.
While the sauce cooks, cook the pasta till al dente. The pasta is going to continue cooking in the sauce so make sure you cook it till al dente.
Season the cream sauce with salt and pepper, add the cooked pasta and salmon, turn off the heat, and cover the skillet. Let the pasta rest for 3-5 minutes. While the pasta rests in the skillet, the sauce will thicken. Uncover, mix well, and enjoy!
Notes
The sauce will seem very thin but once the pasta gets mixed in and it sits for a few minutes it will become super creamy!