Pat chicken breasts dry and season both sides generously with salt, pepper, and 1 tablespoon Cajun seasoning. Heat a 12-inch skillet over medium-high heat until hot, then add olive oil. Once oil shimmers, add chicken and sear 6-7 minutes per side until golden brown with internal temperature of 165°F. Remove from skillet, rest 5 minutes, then slice into strips. Start your pasta water boiling as soon as the chicken goes in the pan.

Bring a large pot of salted water to a rolling boil. Add pasta and cook 8-10 minutes until al dente (tender but still slightly firm when bitten). Before draining, scoop out 1 cup of starchy pasta water and set aside. Drain pasta and toss with a drizzle of olive oil to prevent sticking.

In the same skillet used for chicken (don't wash it), melt butter over medium heat. Add minced garlic and sauté 1-2 minutes until fragrant but not browned. Stir in Cajun seasoning and smoked paprika, letting spices bloom in the butter about 1 minute.

Pour in heavy cream and chicken broth, stirring to combine. Bring to a gentle simmer and cook 4-5 minutes until sauce thickens enough to coat the back of a spoon and looks glossy. Add Parmesan cheese and stir until completely melted and smooth.

Add cooked pasta to the skillet, tossing to coat each piece with creamy Cajun sauce. If sauce seems too thick, add reserved pasta water a splash at a time until you reach desired consistency. Add sliced chicken back to the pan and toss everything together. Remove from heat and garnish with fresh parsley if using.