Temper the egg mixture: Slowly pour a small amount of the hot milk mixture into the egg mixture, whisking constantly to prevent curdling. Gradually add the rest of the milk mixture while continuing to whisk.
Cook the custard: Return the mixture to the saucepan and cook over medium heat, stirring constantly, until thickened and bubbling, about 5-7 minutes. Remove from heat and let cool slightly.
Assemble: Pour the custard over the cooled crust and spread it into an even layer. Refrigerate for at least 2 hours, or until the custard is set.
Make the whipped cream: In a large bowl, beat the heavy cream, powdered sugar, and vanilla extract until stiff peaks form.
Top and Serve: Spread the whipped cream over the set custard layer, creating an even, smooth top. Cut into squares for serving. Garnish with additional whipped cream or white chocolate shavings if desired. Serve chilled.
Prep Time: 20 min | Total Time: 40 min (plus chilling time) | Servings: 9 servings