Separate your eggs first. Use two bowls — crack each egg over one bowl, then transfer the white to your mixing bowl. That way if a yolk breaks, you haven't ruined the whole batch. Don't worry if a little white sneaks into the yolks — that won't hurt the custard. But keep the whites completely free of yolk, or your meringue won't whip up.
Melt your butter. Four tablespoons in the microwave. Set it aside to cool slightly.
Mix your dry ingredients. In a large microwave-safe bowl (you'll need a big one — trust me), whisk together the sugar, self-rising flour, and salt. That little whisk helps break up the flour so you don't get lumps.
Add the wet ingredients. Add the 6 egg yolks and all 5 cups of milk to the dry ingredients. Whisk until smooth. Then pour in the melted butter and whisk that in too.
Cook the custard in the microwave. Put the bowl in the microwave for 3 minutes first. Pull it out and whisk well — it'll still be very liquidy. Then go back in for 2-minute intervals, whisking between each one. As it starts to thicken (usually around the 8–10 minute mark), switch to 1½-minute intervals, and then 30-second intervals right at the end. Total cook time is usually around 12 minutes, but watch your microwave — they all cook a little different. You're looking for a thick, creamy pudding consistency. A little jiggle is fine.
Start the meringue while the custard cooks. In your stand mixer with the whisk attachment, combine the 6 egg whites, ⅓ cup sugar, and ½ teaspoon cream of tartar. Start on medium speed and let it run until you get stiff peaks — the peaks should stand up and not flop over when you pull the whisk out. This takes several minutes. Watch it closely toward the end.
Finish the custard. Once the custard is done, stir in ½ teaspoon vanilla extract and ¼ teaspoon almond extract. Don't skip the almond — it's the whole point.
Let the custard cool a bit. Pour about half the custard into a second bowl. Letting it cool for a few minutes keeps it from cooking your bananas when you layer. You want warm, not hot.
Layer the pudding. In a 9x13 baking dish, lay down a layer of vanilla wafers across the bottom. Slice the bananas right over the dish and scatter them over the wafers. Pour on half the custard and spread it out. Repeat with another layer of wafers, bananas, and the remaining custard.
Top with meringue. Spoon the meringue over the top and spread it all the way out to the edges of the dish — you want it sealed to the sides. Use the back of your spoon to make pretty peaks.
Bake. Pop it in a preheated 350°F oven for 6–10 minutes, until the meringue is browned to your liking. If you like it on the darker side (I do), you might need to bump the oven up a little higher toward the end.
Let it rest. This is the hardest part — wait at least 30–45 minutes before serving. It's still delicious slightly warm, but the custard needs a little time to settle.