Bring a large pot of salted water to a boil and cook spaghetti until al dente
Reserve ½ cup pasta water, then drain and set aside
Toss chicken strips with Cajun seasoning, garlic powder, paprika, salt, and pepper
Heat olive oil or butter in a large skillet over medium-high heat and sear chicken until browned and fully cooked (about 5–7 minutes)
Remove chicken from skillet and set aside
Add butter to the same skillet and sauté minced garlic for 30 seconds until fragrant
Add Cajun seasoning and crushed red pepper flakes, stir briefly to bloom the spices
Pour in heavy cream and chicken broth, simmer 2–3 minutes until slightly thickened
Stir in Parmesan cheese until melted and smooth, adding pasta water if sauce is too thick
Add cooked chicken back to skillet
Stir in spinach until just wilted
Add spaghetti and toss until coated with sauce
Taste and adjust seasoning, add a squeeze of lemon if desired
Serve with extra Parmesan and chopped parsley or green onions
