Begin by bringing a large pot of salted water to a boil. Add pasta and cook until al dente, about 10-12 minutes. Reserve ½ cup of pasta water, then drain the rest.

In a skillet, melt 2 tablespoons of butter over medium heat. Season chicken with salt, pepper, and paprika. Cook chicken for about 6-8 minutes until golden brown and no longer pink. Remove and let rest.

In the same skillet, add remaining butter and melt. Add minced garlic and sauté for about 1 minute until fragrant. Stir in mustard, lemon juice, lemon zest, red pepper flakes, and thyme; let bubble for a minute.

If using, pour in the heavy cream and let the sauce simmer for 2-3 minutes until slightly thickened. Return chicken and drained pasta to skillet, tossing everything together, adding reserved pasta water to adjust consistency.

Plate the pasta hot, garnishing with parsley and additional Parmesan cheese. Enjoy immediately.