Add ice cubes and water to a measuring cup. Cut the butter into ¼" cubes. Place both items in the refrigerator until ready to use.

In a stand mixer bowl, add the flour and salt. Mix using the paddle attachment on the lowest speed for about 10 seconds. Add the chilled butter to the bowl. Mix on low speed until the flour and butter resemble wet sand with pea-sized butter pieces remaining.

Gradually add 1 tablespoon of ice-cold water. Add enough water until the dough looks lumpy and hydrated but not wet or sticky.

Press the dough into a 1” thick round disc and wrap it in plastic, then place it in a resealable bag. Store in the refrigerator to rest for at least 4 hours.

Remove the dough from the refrigerator and allow it to sit at room temperature for about 5 to 10 minutes to make it easier to roll. Roll into a 14-inch circle.

Place the rolled-out dough into a 9-inch pie dish. Trim the excess dough and tuck the excess underneath. Crimp the edges.

Preheat the oven to 375°F (190°C). Place a piece of parchment paper inside the pie dish and add pie weights. Bake for 20 minutes, then continue to bake until golden brown and dry.

Cut the bananas into ¼" slices and layer them on the bottom and sides of the pie shell.

In a small bowl, whisk together sugar and cornstarch. In a medium bowl, whisk together the whole eggs and yolk.

In a medium pot, heat milk, rum, and the whole vanilla bean until hot but not bubbling.

Temper the eggs by slowly whisking in the hot milk. Whisk until thickened, then stir in softened butter.

Strain the custard into the prepared pie shell, smooth out, and cover with plastic wrap. Chill until firm.

Right before serving, whip heavy cream, powdered sugar, and vanilla in a stand mixer until stiff peaks form.

Spread the whipped cream over the pie or pipe with a star tip if desired.

Refrigerate the pie until ready to serve.