01 - Bring a large pot of salted water to a rolling boil. Add the pasta and cook according to package directions until al dente. Reserve 1/2 cup of the starchy pasta water before draining. Set the drained pasta aside.
02 - In a large skillet over medium heat, melt the butter until it begins to foam. Add the minced garlic and sauté for about 1 minute, stirring constantly, until fragrant and lightly golden.
03 - Stir in the Dijon mustard, smoked paprika, crushed red pepper flakes, and Worcestershire sauce. Add the lemon zest and fresh lemon juice. Cook for 1 to 2 minutes, stirring frequently, until the sauce is well blended and aromatic.
04 - Fold in the chopped parsley, chives, kosher salt, and black pepper. Stir until the herbs are evenly distributed throughout the sauce.
05 - Transfer the cooked pasta into the skillet with the sauce. Toss vigorously, adding the reserved pasta water a splash at a time, until a glossy, creamy sauce forms that clings to every strand.
06 - If using shredded chicken or grilled steak, fold it into the pasta now. Continue cooking for 2 additional minutes until the protein is heated through.
07 - Divide among serving bowls immediately. Finish with an extra sprinkle of fresh herbs, grated Parmesan cheese, and a squeeze of lemon from the wedges if desired.