Step 1

Preheat oven to 325 degrees. Wrap ham completely with parchment-lined foil and place on a rimmed baking sheet or roasting pan. Transfer ham to oven and bake 1 1/2 hours.

Step 2

Unwrap ham; discard parchment and foil. With a large, sharp knife score fat in a diamond pattern, making the lines about 3/4 inch apart. Transfer ham to a large roasting pan.

Step 3

Reduce oven temperature to 300 degrees. In a small bowl, mix together brown sugar and Cognac. Brush ham evenly with 3/4 of the brown sugar mixture and return to oven; cook ham 1 hour. Brush ham with remaining brown sugar mixture and continue cooking 30 minutes more. Transfer to a serving platter until ready to carve; garnish with watercress and parsley.