Old Fashion Recipe

Heat milk and cream

In a medium saucepan, combine 2 cups whole milk and 1 cup heavy cream. Add 1 tablespoon unsweetened cocoa powder and 1 cup granulated sugar. Warm over medium heat, stirring occasionally, until sugar dissolves and the mixture is hot but not boiling (steam visible, small bubbles at edges), about 5–7 minutes.

Temper yolks

While the milk warms, whisk 4 large egg yolks in a medium bowl until smooth. Slowly ladle 1/2 cup of the hot milk mixture into the yolks in a thin stream while whisking constantly to temper and raise their temperature.

Finish custard

Pour the tempered yolk mixture back into the saucepan with the remaining milk mixture, stirring constantly. Cook over low-medium heat, stirring and scraping the bottom with a heatproof spatula, until the custard thickens enough to coat the back of the spatula (170–175°F / 77–80°C), about 4–6 minutes. Do not boil.

Add chocolate & flavor

Remove the pan from heat and immediately stir in 4 oz finely chopped bittersweet chocolate, 1 tsp vanilla extract, and a pinch of salt. Stir until the chocolate is fully melted and the custard is smooth.

Cool quickly

Pour the custard through a fine-mesh sieve into a shallow bowl to remove any cooked egg bits. Cover the surface with plastic wrap to prevent a skin from forming. Chill in the refrigerator until cold, at least 2 hours (or up to overnight).

Melt marshmallows

Place 2 cups mini marshmallows, 2 tablespoons light corn syrup, and 1 teaspoon unsalted butter in a small saucepan over low heat. Stir constantly until the marshmallows are melted and glossy, about 3–4 minutes. Remove from heat.

Adjust consistency

If the mixture is too thick to spoon, add 1/2 teaspoon water and stir to loosen. Keep warm; if it thickens while waiting to assemble, briefly reheat over very low heat, stirring.

Spoon custard into dishes

Spoon the chilled chocolate custard into four serving dishes or sundae glasses, dividing it evenly (about 3/4 cup custard per serving).

Add marshmallow topping

Generously spoon or dollop the warm marshmallow mixture over each custard serving, covering the surface. The warmth will soften the custard slightly and create a glossy marshmallow cap.

Finish and serve

Top each sundae with about 2 tablespoons of whipped cream, sprinkle with chocolate shavings or 1/2 teaspoon cocoa powder, and scatter a few toasted chopped pecans if using. Serve immediately while the marshmallow topping is still warm and slightly gooey.