In a small saucepan, heat 2 cups of whole milk over medium heat until it begins to gently boil, stirring occasionally.

Whisk 4 egg yolks with ¾ cup of granulated sugar until fluffy, then mix in ¼ cup of cornstarch until smooth.

Gradually pour in the hot milk, whisking constantly to temper the eggs, then return the mixture to the saucepan and cook over medium heat, stirring continuously until it thickens—about 5 minutes.

Remove from heat, stir in 2 tablespoons of unsalted butter and 1 teaspoon of vanilla extract, then cover and chill for at least 2 hours.

In a cold mixing bowl, add 1 cup of heavy whipping cream with 2 tablespoons of granulated sugar and 1 teaspoon of vanilla extract. Whip on medium-high speed until soft peaks form, then continue until stiff peaks form.

Slice 2 ripe bananas into thin slices. In individual serving cups, layer mini vanilla wafers, a spoonful of chilled pastry cream, banana slices, and top with whipped cream. Repeat layers until cups are filled.

Cover with plastic wrap and refrigerate for 2 to 4 hours before serving. Garnish with a mini vanilla wafer and a banana slice before serving.