2/3 Cup heavy cream
1/4 Cup butter at room temperature
1 Cup sifted confectioners' sugar
1 Large egg yolk
1/4 Cup grapefruit juice
1/4 tsp. grapefruit zest
1/4 tsp. cinnamon
Whip heavy cream in a chilled mixing bowl. Refrigerate until ready to use.
In another mixing bowl, whip butter until fluffy. Gradually blend in confectioners' sugar, and then beat in egg yolk, grapefruit juice, zest and cinnamon.
Fold in whipped cream.
Yield: 1-1/2 cups