A simple liqueur-laced sauce turns simple berries into a sophisticated dessert. Serve in glass goblets or bowls for a pretty effect. The dessert can be assembled and held in the refrigerator up to 8 hours in advance.
Combine the strawberries, 2 tablespoons Grand Marnier, and the sugar in a bowl. Set aside at room temperature for 1 hour.
Meanwhile, sift the confectioner's sugar into a bowl. Whisk in the egg yolk and the Grand Marnier.
Whip the heavy cream until it is almost stiff. Add half of the whipped cream to the confectioner’s sugar mixture to lighten, then fold in the remaining cream.
Place a layer of strawberries in each of 4 wine goblets or bowls. Top with a dollop of Grand Marnier sauce. Layer more berries and sauce in each serving dish. Refrigerate until serving time. Garnish with mint sprigs, if using.