Bring a large pot of salted water to a boil. Cook linguine until al dente. Reserve ½ cup pasta water, then drain.
Season chicken with paprika, chili flakes, salt, and pepper.
Heat olive oil in a large skillet over medium-high heat. Cook chicken until golden and fully cooked. Remove and slice.
In the same skillet, reduce heat and add butter. Once melted, stir in garlic and cook until fragrant.
Add parsley, paprika, cayenne (if using), and lemon juice.
Add a splash of pasta water to create a silky sauce.
Return chicken and pasta to the skillet and toss to coat evenly.
Adjust seasoning and serve hot.