Heat oven to 400ºF.
Toss the banana slices and lemon juice in a small bowl and set aside.
Combine 1/2 cup of the sugar, the corn starch, salt, egg yolks, and whole milk in the carafe of a blender. Blend on high for about 15 seconds. Pour the mixture into a 3-quart saucier and cook over medium-low heat, stirring constantly, until the mixture reaches 172° to 180ºF, 5 to 10 minutes. The mixture will begin to thicken and bubble around the edges. Remove the pan from the heat and whisk in the vanilla.
Spread a small amount of the pudding in the bottom of an oven-safe 1 1/2-quart glass mixing bowl. Cover with a layer of vanilla wafers, followed by a layer of banana slices. Pour one-third of the remaining pudding on top of the bananas and repeat, ending with a layer of pudding.
Whisk the egg whites and cream of tartar in the bowl of a stand mixer on medium speed until soft peaks form, about 2 minutes. Gradually add the remaining 2 tablespoons of sugar and continue whisking until stiff peaks form, about 2 more minutes. Spoon the meringue over the warm pudding, being sure to cover the edges. Bake until the meringue is evenly browned, 8 to 10 minutes. Remove the pudding from the oven and cool for 15 minutes before serving. Cool completely before refrigerating. Refrigerate for up to 3 days.