Whisk together the granulated sugar, cornstarch, and salt in a medium saucepan. Add the milk and cream, then the egg and egg yolk, and whisk until the eggs are well blended. Set the pan over medium-high heat, whisking constantly.

Once bubbles begin popping on the surface and the pudding thickens slightly, about 7 minutes, reduce heat to medium and whisk continuously for 45 seconds for the cornstarch to fully cook. Remove pan from heat.

Add the vanilla and butter and whisk until the butter melts.

Chop two of the bananas into small cubes and the remaining bananas into 1/2-inch coins.

Fold the cubed bananas into the pudding.

Transfer half of the pudding to an 8-inch square pan and spread into an even layer. Top with a layer of cookies, breaking them to fill any gaps. Top the cookies with half of the banana coins, distributing them evenly. Repeat with remaining pudding, cookies, and banana coins.

Set the baking dish on two hot pads in the refrigerator and chill until somewhat cool, 15-30 minutes.

Combine the cream, powdered sugar, and coconut extract in the cooled medium saucepan. Whip with a hand mixer on medium-high speed until medium peaks form when beaters are lifted. Fold in the shredded coconut, if using.

Spread the whipped cream evenly over the pudding. Cover with plastic wrap and refrigerate until completely chilled.

Crush the cookies with your hands and sprinkle decoratively around the edge of the pudding. Slice the banana into coins, if using. Scoop generous portions of pudding onto serving plates and add a few banana coins. The pudding is best eaten within a day of being made, but will keep for two days in the refrigerator tightly wrapped in plastic wrap.