Active Time

　　20 min

　　Total Time

　　2 1/4 hr

　　

Ingredients

Makes 4 servings

　　1/2 tablespoon grated Key lime zest

　　1/2 cup fresh Key lime juice

　　1/2 cup sugar

　　Pinch of salt

　　3 large eggs

　　3/4 stick unsalted butter, cut into bits

　　2/3 cup chilled heavy cream

　　

Step 1

Whisk together zest, juice, sugar, salt, and eggs in a small heavy saucepan. Add butter and cook over medium-low heat, whisking frequently, until thick enough to hold marks of whisk, about 5 minutes. Force through a fine-mesh sieve into a bowl, then quick-chill in an ice bath, stirring occasionally, about 5 minutes.

　　

Step 2

Beat cream until it holds stiff peaks, then fold into custard gently but thoroughly. Spoon into glasses and chill at least 2 hours and up to 12.