In a 1 1/2- to 2-quart pan over high heat, stir 1 1/4 cups canned apricot nectar and 6 tablespoons whipping cream until boiling, about 5 minutes. In a bowl, whisk 5 large egg yolks to blend. Whisk in about half of the hot apricot mixture. Put contents of bowl in pan. Stir over low heat until sauce thickly coats a metal spoon, 8 to 10 minutes. Set pan in a bowl of ice water and stir often until cool, about 8 minutes. If making ahead, chill airtight up to 2 days.