Combine milk and caramel candies in a small saucepan. Cook over medium-low heat until candies melt, stirring frequently. Combine sugar, egg substitute, and cornstarch in a small bowl. Gradually stir about one-fourth of hot mixture into egg substitute mixture; add to remaining hot mixture, stirring constantly. Cook over medium heat, stirring constantly, until mixture is thickened. Remove from heat; stir in vanilla.
Layer half of banana slices and half of caramel mixture in 2 (8-ounce) ramekins. Repeat layers with remaining banana slices and caramel mixture. Arrange vanilla wafers around edge of ramekins. Cover and chill thoroughly. Top each serving with 1 tablespoon whipped topping. Garnish with additional banana slices, if desired.