Cook the pasta in a large pot of well-salted boiling water according to package instructions until al dente. Reserve a small cup of pasta water before draining. Drain and set aside.

Season the chicken pieces generously with salt and black pepper.

Melt the butter in a large skillet over medium heat.

Add the chicken pieces to the skillet and cook, stirring occasionally, until golden brown and fully cooked through. Avoid crowding the pan — cook in batches if needed.

Add the minced garlic and cook for 30 to 60 seconds until fragrant, stirring constantly so it does not burn.

Stir in the Dijon mustard, lemon juice, lemon zest, paprika, red pepper flakes, and dried thyme or Italian seasoning. Stir to coat the chicken and let the spices cook for 30 seconds.

If using heavy cream, pour it in now and stir until combined. Let the sauce come to a gentle simmer for 1 to 2 minutes.

Return the cooked chicken to the pan if removed, then add the drained pasta. Toss until every piece is evenly coated with the sauce. Add a splash of reserved pasta water if the sauce is too thick.

Remove the skillet from heat. Stir in the grated Parmesan cheese until melted and smooth.

Add the chopped fresh parsley and toss once more to combine.

Serve immediately while hot.