Banana Pudding Icebox Cake

Cake:
1 white cake mix + needed ingredients
1/2 c. mashed banana

Custard*:
1 c. sugar
1/2 c. flour
8 egg yolks
4 c. milk
1 t. vanilla

Topping:
16 oz. cool whip, thawed
1/8 t. vanilla
4 bananas, sliced
1/2 c. coarsely crushed vanilla wafers, or graham crackers
1/2 c. chopped pecans, optional

Prepare the cake as directed on box. Add mashed banana until combined. Pour batter into sprayed 9x13 dish. Bake at 350 degrees 25-30 minutes, until toothpick comes out clean.Let cake cool for 5 minutes. Use the handle of a wooden or plastic spoon to poke holes in the warm cake. Combine the sugar and flour in a saucepan. Whisk in egg yolks and then milk. Cook over medium-high heat, whisking constantly, 10-15 minutes, until bubbly and thick. Remove from heat and add 1 t. vanilla. Let cool 10 minutes, stirring occasionally. Pour over warm cake and spread evenly over the top. Cover and refrigerate for 4 hrs. Combine cool whip and vanilla. Uncover cake. Top with sliced bananas, and spread cool whip mixture over top. Sprinkle with crushed cookies and nuts. Serve immediately or refrigerate until ready to serve.

*You can make this using 2 small pkgs of  (banana or vanilla) pudding mix instead, following directions on box for a "classic pudding pie" resulting in a thicker, firmer pudding.