Mix together sugar and cornstarch, and slowly add milk

Cook over low to medium heat, stirring constantly until it thickens. Do not leave unattended.

Slightly beat egg yolks and temper with a small amount of the hot custard; stir well.

Add egg mixture to custard pot and cook 2 more minutes.

Remove from heat and add vanilla and butter.

In a 9x9 baking dish, alternate wafers, then bananas, then pudding.

Beat egg whites and cream of tartar until soft peaks form.

Gradually add sugar until stiff peaks form.

Spread on top of pudding.

Bake until peaks are golden brown.