Line 15x10x1-inch baking pan with wax paper. Spread yogurt into 9×6-inch rectangle in prepared pan. Freeze 30 min.
Arrange bananas along one long side of the yogurt rectangle. Starting at side with bananas, roll up yogurt into log, carefully removing wax paper as you roll. Cover with wax paper. Freeze at least 4 hours or overnight.
Coat yogurt roll evenly with cereal just before serving. Cut into 3/4-inch-thick slices. Store leftover dessert in freezer.