Hold on the thyme on the top for now—you’ll sprinkle it over the top after it bakes. Bake the gratin, uncovered, for 40 to 50 minutes, or until it’s bubbling and golden brown on top.

Instructions . Bring all ingredients to a simmer. Simmer until the sugar is dissolved. Glaze the ham 20 minutes before it's done cooking. Glaze again when there are 10 minutes remaining.