Instructions

1. Combine the cream, sugar and zest in a medium saucepan over medium heat. Place a 2-cup glass liquid measuring cup next to the stove, because you’ll need it to determine when the cream has finished reducing.
2. Bring the mixture to a gentle simmer, stirring frequently to dissolve the sugar, and reducing the heat as necessary to maintain a gentle simmer. (If the mixture begins to boil over, it’s much too hot—briefly remove it from the heat before returning it at a lower temperature). Cook until the mixture is reduced to 2 cups, about 15 to 20 minutes. 
3. Remove the mixture from the heat and stir in the lemon juice and vanilla extract. Let the mixture rest for 20 minutes.
4. Strain the mixture through a fine-mesh strainer into a bowl and discard the zest. 
5. Divide the mixture evenly between 8 individual ramekins or serving glasses.
6. Refrigerate, uncovered, until set, at least 3 hours. Once chilled, possets can be stored in a carton with a lid (or wrapped in plastic wrap) and refrigerated for up to 1 week or frozen for up to 3 months. Unwrap and let them rest at room temperature for 10 minutes before serving (if frozen, allow them to defrost for 30 minutes or longer in the refrigerator). Garnish as desired and serve.