Gingerbread Trifle

I made this gingerbread trifle for Christmas, and it was really good.  Here is the recipe:
Ingredients:
1 13x9 gingerbread cut into 1 inch cubes
5 or 6 Heath bars broken into pieces
2 cups Cool Whip
1 custard recipe (below)

Custard ingredients:
1 1/3 c granulated white sugar
2/3 c all purpose flour
1/2 tsp salt
5 c whole milk
6 egg yolks slightly beaten
1 TBSP vanilla extract

To make the custard:  Combine the first three ingredients in a large, heavy saucepan; whisk in the milk.
Cook over medium heat, stirring constantly until thickened and bubbly.  DO NOT start on high heat - you will ruin the custard. 
Gradually stir about 1/4 of the hot mixture into the egg yolks.
Add this back to remaining hot mixture, stirring constantly.
Cook over medium heat, stirring constantly for three minutes.
Remove from heat.
Add vanilla.
Cool to room temperature.  (Do not refrigerate because it will form a skin and get cold and be difficult to work with)

Assemble trifle in layers in trifle bowl as follows:
1/2 of the gingerbread
1-2 candy bars crushed
1/2 of the custard
1-2 candy bars crushed
1/2 of the whipped topping
Repeat
Garnish the top with crushed candy bar

Keep refrigerated. 
Enjoy!