Method

In saucepan, heat 1 cup 35% whipping cream over medium heat until bubbles form around edge. In bowl, whisk 2 large egg yolks and 1/3 cup granulated sugar until pale. Gradually whisk in hot cream. Return mixture to saucepan and cook over medium-low heat, whisking constantly, until mixture coats back of spoon (do not boil), 3 to 5 minutes. Strain custard through fine sieve placed over bowl.
Stir in 1 tsp each cinnamon and vanilla. Cover surface directly with plastic wrap and refrigerate until cold, about 1 hour. (Make-ahead: Can be refrigerated overnight.)

Makes about 1 1/2 cups.