In this dessert, mixed berries, with their concentrated flavors, are cloaked in a sweet frothy layer of an egg custard, called sabayon in French and zabaglione in Italian. You can use any assortment of berries in these gratins. Beautiful Desserts
Hull the strawberries and slice them lengthwise 1/4 inch thick. In a large bowl, toss together the strawberries, boysenberries, raspberries, kirsch and 2 tablespoons of the sugar. Add a little more sugar if desired, depending on the sweetness of the berries (remember that the topping will also add sweetness).
Place a heatproof bowl over a saucepan of simmering water; do not let the bottom of the bowl touch the water. Add the egg yolks, Champagne, and 4 tablespoons sugar and whisk together until the mixture holds its shape when the whisk is raised, about 6 minutes. Do not overcook or the eggs will scramble. Remove the bowl of sabayon from the heat and place it in a bowl of ice water to cool, whisking occasionally.
In a medium bowl, whip the heavy cream to soft peaks. Fold the whipped cream into the sabayon.
Preheat the broiler. Divide the berries among six 5-inch gratin dishes and set the dishes on a baking sheet. Spread 2 tablespoons of the sabayon over each serving. Sprinkle the remaining 4 tablespoons sugar over the gratins. Slide the baking sheet of gratins under the broiler and cook for 3 to 4 minutes, just until the tops turn golden brown. Watch carefully; turn the baking sheet if necessary. Serve at once.