Season the chicken with salt, black pepper, and garlic powder. Heat olive oil in a skillet and cook chicken 3–4 minutes per side until fully cooked. Remove and set aside.
Boil salted water and cook linguine until al dente. Reserve ½ cup pasta water, then drain.
In the same skillet, melt butter over medium heat.
Add garlic, Dijon mustard, paprika, red pepper flakes, salt, and black pepper. Cook until fragrant.
Stir in lemon juice and heavy cream. Add Parmesan cheese and mix until smooth and creamy.
Return chicken and linguine to the skillet. Toss everything to coat evenly in the Cowboy Butter Chicken Linguine sauce.
Adjust consistency with reserved pasta water if needed. Garnish with parsley and extra Parmesan before serving.