Instructions:
Preheat oven to 350°F (175°C). Line a 9×9 inch baking dish with parchment paper, leaving an overhang on the sides.
Mix graham cracker crumbs, melted butter, and granulated sugar in a bowl. Press the mixture into the bottom of the baking dish. Bake for 10 minutes, then let cool.
In a saucepan, heat whole milk and heavy cream over medium heat until simmering. In a separate bowl, whisk together sugar, egg yolks, vanilla extract, and cornstarch.
Slowly pour a small amount of the hot milk mixture into the egg mixture, whisking constantly. Gradually add the rest of the milk while whisking.
Return the mixture to the saucepan and cook over medium heat, stirring until thickened, about 5-7 minutes. Let cool slightly.
Pour the custard over the cooled crust and refrigerate for at least 2 hours, until set.
Beat heavy cream, powdered sugar, and vanilla extract until stiff peaks form. Spread over the custard.
Cut into squares and serve chilled.
