In a medium saucepan, whisk cornstarch, sugar, and salt together. In a medium sized bowl, beat the egg yolks together until they are a pale yellow color, about 2-3 minutes. Add half and half to the eggs and whisk together well. Pour mixture slowly into the saucepan while whisking quickly.

Cook the pudding over medium flame, whisking constantly, until the pudding is thickened and bubbling slightly.

Take off the heat and stir in the vanilla and butter. Allow to cool for 5 minutes, stirring occasionally to prevent pudding skin (unless you like pudding skin).

Using a fine mesh sieve over a large bowl, strain the pudding into the bowl and cover with plastic wrap touching the top of the pudding. Refrigerate until cool.

In an oven-safe dish (or a trifle bowl if you aren't making meringue) layer the vanilla wafers at the bottom, then a layer of bananas, then a layer of custard. Repeat until the dish is full or you run out of layering ingredients.

Preheat oven to 325 degrees F.

FOR MERINGUE: In a large, clean bowl use a hand mixer to whip up the egg whites until foamy. Add cream of tartar, then whip until the whites are no longer foamy, but smooth looking.

Add powered sugar, 1 tablespoon at a time, then vanilla extract and continue mixing until stiff peaks form.

Spread meringue over the baking dish, reaching from edge to edge. Use a spatula or spoon to create peaks on the meringue for browning and decoration.

Bake for 20-25 minutes, or until the meringue has browned. Let cool slightly before serving.