Place the ham in a large, oven proof casserole. In a small bowl, combine the lemon juice, laurel leaves, rosemary and garlic and pour the mixture over the ham, rubbing all over to make sure that it is evenly covered. Cover with plastic wrap and refrigerate for 12 hours.
Preheat the oven to 375 degrees F.
Cover the ham with aluminum foil and bake in the oven 1 1/2 hours, turning it occasionally.
Remove from the oven, baste with the wine and grappa and return to the oven to cook uncovered for another 1 1/2 hours.
Remove the ham from the oven and place it on a rack to cool.
Remove the excess grease from the pan and place the pan over low heat.
Add the chicken stock and stir with a wooden spoon over medium-low heat to dislodge the browned bits from the pan.
Whisk in the flour and butter and continue to stir over low heat until the pan juices thicken and form a gravy. Season, to taste, with salt and pepper and remove to a small bowl or gravy boat.
Slice the ham and serve immediately with the gravy.
