Preheat oven to 350 degrees Fahrenheit (180 degrees Celsius).

Rinse and pat corned beef dry. Lay in the center of a long piece of aluminum foil (at least 30 inches). Smear Dijon mustard over the entire top of the meat. Sprinkle brown sugar evenly over the mustard.

Bring the edges of the foil together and seal, leaving space between the meat and the foil for a tent effect. Seal the sides well.

Transfer the meat to a baking pan. Bake for two and a half hours (if using a smaller corned beef, bake for just two hours). Remove from oven.

Open the foil carefully so you don’t get burned by escaping steam. There will be a lot of liquid surrounding the meat. Save this for serving.

Raise oven temperature to broil. Combine the jelly and bourbon. Smear over the entire top of the meat.

Broil four to five minutes on the middle rack of the oven. Cool for 15 minutes and slice. When serving, drizzle with some of the reserved liquid.