Lemon posset is made by heating cream and sugar to a boil, then adding lemon juice. It chills into a thick and velvety custard, although it contains no eggs, cornstarch, or gelatin. Paired with a simple cookie crust, this humble dessert becomes an elegant lemon tart.
The crust calls for digestive biscuits, British cookies that taste very similar to graham crackers. Digestive biscuits are typically found in the international aisle of grocery stores, British import shops, and online. If you can’t find digestive biscuits, graham crackers will work just as well.
- Make the crust: Heat the oven to 350°F. Place cookies in the bowl of a food processor and pulse until they are broken down into fine crumbs. Pour in the melted butter and pulse again until the mixture resembles wet sand. Alternatively, you can place the cookies in a gallon-size Ziploc bag and smash them with a rolling pin or meat tenderizer into fine crumbs. Empty crumbs into a medium mixing bowl and pour in the melted butter. Toss with your hands until the mixture resembles wet sand.
- Press a little more than half of the crumb mixture into the bottom of a 10-inch tart pan with a removable bottom. Press the remaining mixture into the sides of the pan. Make sure the crumbs are as compacted as possible by using the flat part of your fist or the bottom of a measuring cup or drinking glass to firmly pack and smooth the mixture against the pan.
- Bake the crust for 8–10 minutes or until nicely browned and smelling toasty. Set aside to cool while you make the filling.
- Make the filling: Place the heavy cream, sugar, and salt in a medium saucepan over medium-high heat. Bring the mixture to a simmer, stirring occasionally to prevent scalding and to encourage the sugar to fully dissolve. Let simmer for 1 minute.
- Remove the pan from the heat and pour in the lemon juice. Stir well—the mixture will immediately begin to thicken.
- Carefully pour the filling into the prepared crust. If you pour too quickly or from too high a height, some of the crumbs from the crust may loosen and end up floating in the filling—a purely cosmetic issue, but one that can be avoided by pouring slowly and gently.
- Chill the tart uncovered for at least two hours or until fully set. Once the filling is set, you may cover the tart with plastic wrap. Serve cold, topped with fresh fruit or as is. This tart is best eaten the day it’s made, as the crust will get soggy over time, but it will keep in the refrigerator, tightly covered, for up to 2 days.
Zola Gregory is a writer and recipe developer based in Seattle. Having previously worked as a pastry chef and baker, she now enjoys helping others find success in their own kitchens through her stories, recipes, and baking classes.