1. Rub the chicken breasts with Cajun seasoning. Heat olive oil in a skillet over medium-high heat and sear the chicken until golden and cooked through, about 6-7 minutes per side. Remove and let rest before slicing thinly.

2. In the same skillet, melt butter and add red onion, garlic, and jalapeño. Cook until softened and fragrant, about 3 minutes.

3. Pour in the heavy cream and bring to a gentle simmer. Stir in the Parmesan cheese and season with salt and pepper. Add red pepper flakes if you want it spicier.

4. While the sauce simmers, cook the linguine according to package instructions. Drain and reserve some pasta water.

5. Add sliced chicken and cooked pasta to the sauce. Toss well to coat, adding a splash of pasta water if needed to loosen the sauce.

6. Plate the pasta and garnish with fresh parsley. Serve hot with extra Parmesan and a squeeze of lemon if desired.