Cut Sugar Biscuits in half; brush cut sides evenly with 5 tablespoons orange liqueur.
Line bottom of a 4-quart bowl or trifle bowl with eight Sugar Biscuit halves. Arrange strawberry halves around lower edge of bowl. Spoon one-third of Trifle Custard evenly over Sugar Biscuit halves; top with one-third of remaining strawberry halves. Repeat layers twice, ending with strawberry layer. Drizzle remaining orange liqueur evenly over top. Cover and chill 3 to 4 hours.
Beat whipping cream until foamy; gradually add powdered sugar, beating until soft peaks form. Spread over trifle; serve immediately. Garnish, if desired.