Whisk one large egg with 1/4 cup of granulated sugar until pale yellow and frothy, about 2 minutes. Set aside.

Sift in 2 tablespoons of all-purpose flour and 1 tablespoon of cornstarch into the egg mixture. Stir gently until well combined.

In a saucepan, heat 2 cups of whole milk over medium heat until it simmers, about 5 minutes. Remove from heat.

Gradually pour half of the warm milk into the egg mixture while whisking continuously to temper the eggs.

Pour the tempered mixture back into the saucepan with the remaining milk. Cook over low heat, stirring constantly, for about 3-4 minutes until thickened.

Transfer the custard to a clean bowl, cover with plastic wrap directly on the surface, and cool at room temperature for about 30 minutes.

Crush about 10 Oreo cookies in a food processor or a zip-top bag until fine crumbs.

In a separate bowl, whisk 1 cup of heavy cream until soft peaks form. Be careful not to overwhip.

Gently fold the crushed Oreos into the cooled custard, then fold in the whipped cream until light and homogeneous.

Spoon the mixture into serving bowls or glasses and refrigerate for at least 2 hours. Add optional pearl sprinkles before serving.