Preheat oven to 300 degrees. Grease a 13X9X2" pan. Reserve 1 cup dry cake mix for filling.
For crust: Mix together remaining cake mix, 1 egg, oil and 1/2 cup brown sugar (mixture will be crumbly). Press mixture evenly on bottom and three-fourths of way up sides of pan. Arrange banana slices on crust.
For filling: Blend cream cheese with remaining 1/2 cup brown sugar in large mixer bowl. Add remaining 3 eggs and 1 cup reserved cake mix. Beat 1 minute at medium speed. Turn to low speed. Add milk and lemon juice, mixing until smooth. Turn into crust.
Bake at 300 degrees for 45 to 55 minutes or until center is firm. Cool on rack. Spread topping over cooled cake. Refrigerate until serving time.