Whisk together 2 cups of whole milk, ¾ cup of granulated sugar, ¼ cup of cornstarch, and a pinch of salt in a medium saucepan until smooth. Set over medium heat, stirring until it simmers and thickens, about 5-7 minutes. Remove from heat and cool slightly.

In a separate bowl, whisk 4 large egg yolks until smooth. Gradually add ½ cup of the warm milk mixture into the yolks, whisking vigorously. Pour the tempered yolk mixture back into the saucepan, stirring constantly.

Return saucepan to medium heat and cook until thickened, about 3-5 minutes, stirring constantly. Remove from heat and stir in 2 tablespoons of unsalted butter, 1 teaspoon of vanilla extract, and 1 teaspoon of banana extract if using. Pour into a bowl, cover with plastic wrap, and refrigerate until chilled.

Once chilled, fold in 2 cups of thawed whipped topping gently until smooth. Set aside.

Brew 1 cup of strong coffee and cool. If desired, mix in banana liqueur. Pour into a shallow dish.

Slice 2 ripe bananas into rounds and toss with a tablespoon of lemon juice to prevent browning.

Dip each ladyfinger into the coffee mixture for about 2-3 seconds per side. Arrange in a single layer in a 9x13-inch dish. Spread half of the banana pudding mixture over the ladyfingers and layer half of the banana slices on top.

Repeat with another layer of soaked ladyfingers, remaining banana pudding mixture, and top with remaining banana slices.

Cover with plastic wrap and refrigerate for at least 4 hours or overnight.

Before serving, dust the top with unsweetened cocoa powder and serve.