Preheat the oven to 350°F (175°C). In a bowl, combine graham cracker crumbs and melted butter. Press mixture into the bottom of a greased 9x9 inch baking dish.

Make the custard

In a mixing bowl, whisk together sugar, eggs, key lime juice, sweetened condensed milk, and lime zest until smooth. Pour over the crust.

Bake

Bake for 20-25 minutes until the custard is set. Let it cool to room temperature, then refrigerate for at least 2 hours before cutting into bars.

Lilikoi Ice Cream

Prepare ice cream base

In a saucepan, whisk together heavy cream, whole milk, and sugar. Heat over medium until sugar dissolves. In a separate bowl, whisk egg yolks. Slowly pour in hot cream mixture while whisking. Return to heat and cook until slightly thickened.

Add lilikoi puree

Remove from heat and stir in lilikoi puree. Chill mixture in the refrigerator for at least 2 hours.

Churn and freeze

Pour chilled mixture into an ice cream maker and churn according to manufacturer's instructions. Freeze until firm.

Vanilla Bean Whip

Whip cream

In a mixing bowl, combine heavy whipping cream, powdered sugar, and vanilla bean paste. Whip until soft peaks form.

Assembly

Serve

Cut key lime custard bars into squares and place on a serving plate. Scoop lilikoi ice cream on top, add a dollop of vanilla bean whip, and sprinkle with popping boba.