Baking berries and custard into a gratin should yield firm but juicy fruit, a creamy topping, and a crisp crust—if the heat doesn’t ruin the plan. For a berry gratin recipe with firm but juicy fruit, frothy zabaglione, and a lightly browned crust, we discovered a few tricks. Tossing the berries with sugar and a pinch of salt helped draw out their juices. Cooking the custard over low heat prevented it from curdling, and whipping it longer than usual gave it great texture. For the thickest, most flavorful custard, we added whipped cream and a few spoonfuls of Sauvignon Blanc (which we prefer to Marsala for its clean flavor). A sprinkling of granulated and brown sugar provided the caramelized crust. The resulting fresh berry gratin recipe was juicy, light, and creamy, just what we were looking for.