Spoon yogurt onto several layers of heavy-duty paper towels; spread to 1/2" thickness. Cover with additional paper towels; let stand 5 min. Scrape yogurt into a bowl, using a rubber spatula.
Arrange half of cake cubes in a 2 qt trifle bowl. Spread half of pudding mixture over cake. Drizzle jam mixture evenly over pudding. Arrange 1 C of sliced peaches over jam mixture. Repeat layering procedure with remaining cake, pudding, and peaches. If desired, garnish with sliced strawberries and mint sprigs.