Whisk the yolks and sugar (2–3 minutes) – In a medium mixing bowl, whisk together the egg yolks and sugar until pale, smooth, and slightly thickened.

Heat the milk (5–6 minutes) – In a large saucepan, gently heat the milk over medium heat until it’s steaming and small bubbles form at the edges. Do not let it boil.

Temper the eggs (2 minutes) – Slowly pour about 1 cup of the hot milk into the egg mixture while whisking constantly. This prevents the eggs from scrambling.

Combine and thicken (8–10 minutes) – Pour the tempered egg mixture back into the saucepan with the remaining milk. Cook over medium-low heat, stirring constantly with a wooden spoon. Heat until the custard thickens enough to coat the back of a spoon or reaches 170–175°F.

Cool and flavor (1–2 minutes) – Remove from heat, stir in the vanilla extract, and let cool for 15–20 minutes.

Chill and serve – Transfer to a pitcher, cover, and refrigerate for at least 2 hours. Serve cold in punch cups with a sprinkle of nutmeg.