Like many good recipes, it was born from needing to use up ingredients: a half-used container of buttermilk left over from pancakes and a wilting rosemary plant that I'd translated then abandoned to wilt during a week of no rain. Huzzah! Buttermilk Rosemary Ice Cream.
This recipe following the basic custard-method: whisk hot cream into egg yolks and sugar, strain, cook into a custard. The buttermilk is saved until the end to prevent it from curdling under duress of the heat.
Buttermilk Rosemary Ice Cream
1 cup half and half
1/2 cup cream
3 tablespoons fresh rosemary leaves, finely minced
6 egg yolks
1 cup sugar
2 1/2 cups buttermilk, chilled in the freezer for at least 20 minutes
In a medium-sized saucepan, simmer half and half, cream and rosemary over low heat for 2 minutes, or until just beginning to bubble.
In a metal bowl, whisk together egg yolks and sugar. Pour hot cream mixture into egg yolk mixture very slowly while vigorously whisking. Return mixture to saucepan and cook gently over medium-low heat, stirring constantly. Do not allow to boil. After 3-5 minutes when mixture has begun to thicken and registers 170 - 175°F on an instant-read thermometer.
Strain through a fine-mesh sieve into a bowl with the chilled buttermilk and stir well.
Cover with plastic wrap and chill for at least an hour or until cool to the touch.
Process in ice cream machine according to manufacturer's instructions. Ice cream may need to rest in the freezer for an additional hour or two after processing in order to harden.
Will keep, stored in a sealed container, for up to one week.