Separate the eggs and set the whites aside. Place the yolks in a small saucepan.
Lightly mix the egg yolks with a whisk or fork.
Whisk in the espresso, cocoa powder, ¼ cup (50 g) of the sugar, and ½ teaspoon of the vanilla.
Turn the heat to low and cook for a minute or two while whisking constantly. It won’t take long for the mixture to thicken. When it does, immediately remove from the heat and, using a rubber spatula, turn into a medium bowl. Be sure to get all of the yummy mixture from the sides of the saucepan into the bowl, too. Set aside to cool to room temperature.
In a stand mixer, or with a handheld electric beater, whip the egg whites with 2 more tablespoons of sugar until you have medium-stiff peaks. With a rubber spatula, gently fold the whipped whites into the cooled coffee-cocoa mixture.
In a stand mixer or with a handheld electric beater, add the heavy cream, remaining 1 teaspoon vanilla, and coffee extract. Whip on high while raining (sprinkling) in the remaining ¼ cup (50 g) sugar until the peaks hold their shape. With a rubber spatula, gently fold into the filling.
Lay the sliced bananas in the bottom of the cookie crumb crust.
Lightly spread the filling over the bananas and freeze overnight.
Before serving, drizzle the chocolate sauce and sprinkle the optional chopped pistachio nuts over the top of the pie.