Remove the chicken breast from the refrigerator 30 minutes prior to cooking. Preheat your oven to 375 degrees.
Pat the chicken dry and season well with kosher salt and pepper. Heat an oven-proof skillet over medium high heat and add the margarine.
When the margarine is melted and bubbly, sear the chicken breast for 2-3 minutes each side until nicely browned.
Immediately transfer the skillet and chicken to the pre-heated oven and cook for 15-20 minutes. Thinner breasts will take 15 minutes, thicker breasts will take 20. Check the internal temperature of the chicken with an instant read thermometer. The chicken is done when the thermometer registers 165 degrees in the thickest part of the breast.
Remove from the oven and place the chicken on a plate to rest for about 5 minutes before slicing. Serve immediately or place in an air-tight container in the refrigerator for up to 5 days.