Grand Marnier Souffle

Name: Grand Marnier Souffle
Ingredients: Pastry Cream:; 2 cups plus 2 tablespoons whole milk; Zest of 1 lemon; 2 1/2 ounces/70 g superfine sugar; 2 1/3 ounces/65 g all-purpose flour; 4 large eggs; Souffle:; 2/3 ounce/20 g unsalted butter; 6 1/8 ounces/175 g superfine sugar, plus more for coating; 12 1/3 ounces/350g egg whites (from 4 eggs); 1/4 cup/5 cl orange liqueur, such as Grand Marnier; 2/3 ounce/20 g potato starch; 1/3 ounce/10g confectioners' sugar