Prepare the Crust: In a medium bowl, combine graham cracker crumbs, melted butter, and sugar. Mix well until all crumbs are moistened.
Press the Crust: Press the crumb mixture firmly into the bottom of a 9x13 inch baking pan. A flat-bottomed measuring cup can aid in creating an even surface.
Chill the Crust: Place the prepared crust in the refrigerator to chill for at least 30 minutes while preparing the filling. This will help it firm up.
Prepare the Filling: In a large bowl, beat the softened cream cheese until smooth and creamy.
Add Sweetened Condensed Milk: Gradually add the sweetened condensed milk to the cream cheese, mixing until well combined and smooth.
Incorporate Ube Flavor: Stir in the vanilla extract and ube halaya (or ube extract). Mix until evenly distributed. If using ube extract, add purple food coloring gradually to achieve the desired shade of purple. Be cautious not to over-color.
Pour Filling over Crust: Pour the ube cheesecake filling over the chilled crust, spreading evenly.
Chill the Cheesecake Bars: Cover the pan with plastic wrap and refrigerate for at least 4 hours, or preferably overnight, to allow the cheesecake to set completely.
Cut and Serve: Once the cheesecake has set, cut it into bars. Use a sharp knife and wipe it clean between each cut for neat slices.
Optional Garnish: Dust with ube powder, top with whipped cream, or drizzle with melted white chocolate before serving, if desired.