1/2 cup sugar
2 tablespoons cornstarch
1 can (12 ounces) evaporated milk, plus 1/2 cup milk to equal 2 cups total
2 large egg yolks
1 tablespoon vanilla extract, divided
1 cup heavy cream
48 vanilla wafers
3 bananas peeled and sliced
Whisk sugar, cornstarch, and salt in a medium saucepan. Just before adding milk, whisk in egg yolks, and then turn heat to medium and vigorously whisk in milk. Continue to whisk occasionally and more frequently as it heats, until mixture boils and thickens to pudding consistency; remove from heat; stir in 2 teaspoons of the vanilla. Cover with a sheet of plastic wrap directly on the surface to keep a skin from forming; cool to room temperature.
When ready to assemble, whip cream with remaining teaspoon of vanilla to soft peaks. Arrange 4 vanilla wafers in each of 6 wide goblets. Add a few banana slices to each goblet. Top with a generous 2 tablespoons each of pudding and whipped cream. Repeat, arranging 3 vanilla wafers in each goblet, along with a few more banana slices, and a couple generous tablespoons each of remaining pudding, and cream. Garnish with remaining vanilla wafer and a few banana slices. Cover and refrigerate until cookies soften, a couple of hours and up to overnight.