Start with your pre-baked pie crust. If you're using a store-bought crust, just make sure it's cool before adding any filling. If making homemade, allow it to cool completely after baking.

In a medium saucepan, combine the milk, sugar, cornstarch, and salt. Whisk to combine and cook over medium heat, stirring continuously to avoid lumps.

Once the mixture begins to thicken, temper the egg yolks by whisking them in a separate bowl and gradually whisking in about a cup of the hot milk mixture. Then, pour the egg mixture back into the saucepan.

Continue cooking while stirring for another 2-3 minutes, or until the mixture is thick and bubbly. Remove from heat and add the butter and almond extract (if using). Mix until smooth.

In your prepared pie crust, layer the sliced bananas evenly until the bottom is covered. Pour the custard over the bananas and spread it evenly.

Cover the pie with plastic wrap and refrigerate for at least 4 hours, or until set.

When ready to serve, whip the heavy cream until soft peaks form. Gradually add the powdered sugar and vanilla extract, then continue to whip until you achieve nice peaks.

Spread the whipped cream on top of the pie just before serving. For a decorative touch, you can slice a few bananas and garnish the top!