Summer Berries & Elderflower Gratin

You can use any assortment of summer berries in this dish and it always tastes great. Traditionally, the recipe uses champagne or marsala wine in the gratin sabyon, but I replace them with St. Germain elderflower liqueur or my own elderflower cordial. I make this by picking fresh elderflower flowers in late May and June and infusing them in a syrup with lemon juice.