- 1 cup heavy cream
- 1 cup milk
- 6 large egg yolks
- 1 cup elderflower concentrate (see Note)
- In a large saucepan, heat the cream and milk until beginning to steam. Set a heatproof medium bowl in a large bowl of ice. In another bowl, whisk the egg yolks with the elderflower concentrate until smooth. Gradually whisk in the hot cream.
- Return the mixture to the saucepan and cook over moderate heat, stirring gently with a wooden spoon, until the custard coats the back of the spoon, about 6 minutes; do not let it boil. Strain the custard into the bowl in the ice bath and let cool completely, stirring often.
Make Ahead The sauce can be refrigerated for up to 1 day. Notes Elderflower concentrate, made in England from elderflowers and lemons, is available by mail from Mushrooms & More, 914-682-7288.