Measure and prepare all ingredients. Set up a large pot of water for the pasta. Pat the chicken breast fillets dry with paper towels and trim away any tendons or excess fat. Slice very thick fillets horizontally or gently flatten them so they cook evenly. Season the chicken on both sides with salt and black pepper. Peel the onion and cut it into fine dice. Peel and finely chop the garlic or press it through a garlic press. Wash the parsley, shake it dry, remove the leaves and chop them finely.

Bring the pasta water to a boil and season it generously with salt. Heat the vegetable oil in a large frying pan over medium-high heat. Place the chicken breast fillets in the hot pan and sear the first side for about four to five minutes until golden brown. Turn the fillets and cook the second side for another three to five minutes, until the chicken is fully cooked. Remove the cooked chicken from the pan, place it on a plate and cover it loosely.

Melt the butter in the same pan, loosening the browned bits with a wooden spoon. Add the diced onion and sauté for two to three minutes until translucent. Add the garlic and tomato paste and cook for about 30 seconds. Sprinkle the brown sugar evenly into the pan and allow it to melt briefly.

Carefully deglaze the pan with the mulled wine and stir thoroughly. Add the orange zest, cinnamon and clove. Reduce the mulled wine mixture over medium-high heat for about five to seven minutes. Pour in the chicken stock and gently simmer the sauce for another five minutes.

Meanwhile, cook the pasta until al dente according to the package instructions. Before draining, reserve about 100 milliliters of the pasta cooking water. Drain the pasta in a colander and allow it to drain briefly.

Stir the cream and mustard into the mulled wine sauce. Let the sauce cook over low heat for another three to four minutes. It should only simmer gently. Mix the cornstarch with two tablespoons of cold water until smooth. Gradually add the cornstarch mixture to the simmering sauce, stirring constantly until the desired thickness is reached. Season the sauce with salt and pepper. If it is too intense, stir in a little reserved pasta water.

Return the chicken breast fillets and their resting juices to the pan. Warm the chicken in the sauce over low heat for two to three minutes without allowing the sauce to boil vigorously.

Divide the pasta between warmed plates. Slice the chicken if desired and arrange it on top of or beside the pasta. Spoon the mulled wine sauce over the chicken and pasta. Sprinkle with chopped parsley and serve the dish immediately while hot.