Preheat the broiler with the rack in the middle.
Make the pudding: In a saucepan over medium heat, whisk the 3/4 cup sugar, cornstarch, milk, egg yolks together. Stir constantly, until mixture just begins to bubble about 10-15 minutes. Reduce the heat to a simmer and whisk for another minute. Remove from the heat and whisk in the vanilla, salt and butter. Transfer to a bowl to cool.
Make the meringue: Simmer 1 inch of water in a saucepan. Place the egg whites, 1/2 cup of sugar and cream of tartar in a heat proof stand mixer bowl. Place this bowl over the simmering water and whisk continuously until the sugar is dissolved and the mixture is hot about 3 minutes. Place the bowl in the stand mixer fitted with the whisk and beat until stiff peaks form about 5-7 minutes.
Line an oven safe pie dish or 13x9 inch pan with a layer of vanilla wafers. Place 1/2 banana slices over that. Pour 1/2 of the custard over the cookies and bananas. Layer with more cookies, bananas and pudding. Finally, layer on the meringue with a spatula, spreading with flicks of the wrist to make peaks.
Broil for 3-7 minutes until the peaks of the meringue are a nice golden brown. Dust with cinnamon or nutmeg if desired. Ready to serve at any temperature.