In a small saucepan over medium heat, heat the orange juice for about 10-12 minutes, stirring occasionally, until reduced by half. Set aside to cool.

In a separate medium saucepan over medium-low heat, whisk together granulated sugar, cornstarch, and baking soda. Slowly whisk in whole milk, ensuring no lumps. Continue whisking until the mixture begins to steam, about 5 minutes.

In a small bowl, whisk the egg yolks. While whisking, slowly drizzle in about 0.25 cup of the warm milk mixture to temper the eggs.

Pour the tempered egg mixture back into the saucepan with the rest of the milk mixture, stirring constantly.

Keep cooking over medium-low heat, stirring continuously, for 5 to 7 minutes, or until the custard thickens and coats the back of a spoon.

Remove from heat. Immediately whisk in the reduced orange juice, vanilla extract, orange zest, and unsalted butter until smooth.

Pour the custard into 3 small serving cups or ramekins. Let cool at room temperature for about 30 minutes, then cover and refrigerate for at least 3 hours.

When ready to serve, top with whipped topping and garnish with fresh mint and orange zest.