Banana Cream Layer Cake

To prepare cake: Preheat oven to 375°F. Coat two 9-inch round cake pans with cooking spray and line the bottoms with wax paper or parchment paper. Whisk eggs, 1 cup sugar and oil in a large bowl. Stir in mashed bananas, buttermilk and 1 teaspoon vanilla. Stir whole-wheat flour, all-purpose flour, baking powder, baking soda and salt in a medium bowl. Add to the banana mixture and fold in just until blended. Divide the batter between the pans. Bake the cake until the tops spring back when touched lightly, 20 to 25 minutes. Let cool for 5 minutes, then turn out onto a wire rack and let cool completely. To prepare Bavarian cream: Place milk in a small saucepan, sprinkle gelatin over the milk and let stand for 1 minute to soften. Stir in 2 tablespoons sugar and heat over medium heat, stirring to dissolve the gelatin. Stir in 1/2 teaspoon vanilla and transfer to a medium bowl. Refrigerate, stirring occasionally, until the mixture has thickened to the consistency of raw egg whites, 40 to 45 minutes. Beat whipping cream until soft peaks form. Whisk one-third of the whipped cream into the milk mixture. Fold in the remaining whipped cream. Refrigerate until set and thickened to the consistency of whipped cream again, about 1 hour. To assemble cake: Shortly before serving, place 1 cake layer on a serving plate and spread half the Bavarian cream over it. Peel and slice the remaining bananas; arrange half the slices evenly over the cream. Top with the second cake layer. Spread the remaining cream over the cake and arrange the remaining banana slices decoratively over the top.