• For banana cream pudding
• In a medium saucepan, whisk cornstarch, sugar, and salt together. Add the egg yolks and milk in and whisk well.
• Cook the custard over medium-low heat, whisking occasionally, until the pudding is thickened and bubbling, about 7 minutes.
• Once bubbling, continue cooking for another minute, giving it a good whisk (but not vigorously).
• Take off the heat and gently stir in the unsalted butter, vanilla extract, and banana cream extract.
• 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.

FOR MERINGUE

• Put the sugar and water into a small saucepan over medium-low heat, attaching a candy thermometer to the pot. Once the sugar dissolves, turn the heat to medium-high and wait for it to boil.
• While the sugar and water are cooking: in a large, clean stand mixer bowl with the whisk attachment whip up the cold egg whites until foamy on medium speed. Add the cream of tartar, if using, and briefly whip again on medium speed, keeping the eggs foamy. Do not whip them into peaks.
• Cook the sugar syrup to 240 degrees F (116 degrees C). Once there, take off the heat and immediately bring the pan to the egg whites in the stand mixer.
• Begin whipping the egg whites on high speed and CAREFULLY pour the hot sugar syrup into the bowl of whipping egg whites. Do NOT pour it directly onto the whisk because it can fling hot sugar onto you.
• Let the egg whites keep whisking at high speed for about 7 minutes, or until the bowl is around body temperature. The meringue should be extremely fluffy, glossy, and white.
• Store the meringue covered with plastic wrap in the fridge for up to 3 days until ready to use.
• 
  To Serve
• In a pretty trifle bowl, serving dish, individual dishes, or a 9 inch baking dish (depending on how you want to serve your banana pudding), begin layering the Nilla wafers, banana slices, and your homemade pudding. Keep layering them until you run out of either space or ingredients.
• Once your servingware is full, top the pudding generously with your meringue from edge to edge.
• If baking, bake the dish at 350 degrees F (180 degrees C) for about 25-30 minutes, until the top of the meringue is becoming golden and toasty. Serve warm or chill in the fridge for 4 hours before serving.
• If NOT baking, use a culinary torch to brown the top of the meringue and serve either room temperature or chilled.