Ham and Parsley Terrine

Name: Ham and Parsley Terrine
Ingredients: 2 small onions, peeled and studded with 3 cloves each; 3⁄4 cup finely chopped flat-leaf parsley leaves, stems reserved; 10 black peppercorns; 4 unsmoked ham hocks (about 4 lbs.); 3 carrots, halved crosswise; 2 ribs celery, halved crosswise; 2 bay leaves; 2 fresh thyme sprigs; 1 (750-ml) bottle dry white wine; 1 oz. gelatin; Kosher salt, to taste; 1 3⁄4 lb. unsmoked cooked ham, cut into 3⁄4″ cubes; 2 shallots, finely chopped; 1 clove garlic, finely chopped