1Preheat oven to 350. Line bottom of 8 inch square pan with wax paper; spray sides with cooking spray.
Sift together flour, dry milk, pudding mix and baking powder in a bowl; set aside.
2In large mixing bowl, combine egg yolks and sugar; using electric mixer, beat 2 minutes.
Alternating ingredients, gradually beat in pudding mixture and milk; add vanilla. Beat a medium-high until mixture is combined. The mixture will be very thick at this stage. But it will turn out fine.
3In separate bowl, using clean beaters, beat egg whites with salt until stiff peaks form. Gently stir 1/4 of beaten egg whites into batter; carefully fold in remaining egg whites.
Pour batter in baking pan; bake 25-30 minutes until cake tester comes out clean.
4Let cake cool 5 minutes; remove from pan. Set on wire rack to cool; remove wax paper from cooled cake; transfer cake to serving platter and spread top with whipped topping. Peel and slice bananas; transfer slices to small bowl, add lemon juice and toss gently. Decoratively arrange banana slices over whipped topping.