Heat the milk and heavy cream with half of the sugar, reserving the rest for later, and 1 tsp freshly ground nutmeg. Remove from heat when the sugar is dissolved. Do not boil.
Whisk together the yolks with the remaining 1/2 cup sugar until pale yellow and thickened.
Stream a few tablespoons of the hot milk mixture into the egg yolk mixture and whisk to combine.
Pour this mixture back into the pot. Return to heat and cook over a medium-low flame until thickened (this will usually happen a minute or so after the first bubbles break through). Stir continuously. Once thickened, strain all the goupy stuff out.
Chill and prepare according to manufacturer’s instructions.