Lemon Posset: the classic English lemon custard that only needs 3 ingredients
Few desserts convey British elegance and the simplicity of a grandmother’s recipe as well as Lemon Posset.
At a time when menus were full of preparations loaded with thickeners, clarified butter and eggs, this sweet survived precisely because it dispensed with all the confectionery paraphernalia: just fresh cream, sugar and the juice – plus the zest – of a lemon.
No flour, no starch, no eggs. The result is a silky cream that sets on its own thanks to the alchemy of milk fat and citric acidity.
Below you’ll find the historical origins of posset, the chemical explanation behind what makes the cream thicken naturally, a detailed step-by-step guide—including sweetened and fruity variations—presentation suggestions, and storage tricks.
Everything is in clear, direct Portuguese, but with that touch of curiosity that transforms a simple recipe into kitchen culture.
Understanding the Magic of Gelatin-Free Coagulation
What thickens posset isn’t prolonged heat or starch, but the action of citric acid on casein, the main protein in milk. When lemon juice comes into contact with hot cream, it lowers the liquid’s pH. The casein micelles—normally stable thanks to their electrical charge—lose this stability, bonding with each other, and forming a network that traps water.
The fat in the cream contributes to its velvety texture while providing extra structure. That’s why the recipe calls for fresh cream with at least 30% fat: the high fat content ensures a firm texture without the risk of it becoming too curdled.
Mandatory and optional ingredients
300 ml of very cold fresh cream (do not use light or carton versions).
60g granulated or refined sugar. Can be substituted with 50g coconut sugar, 45ml maple syrup, or other oven and stovetop sweeteners (adjust as needed, as each product has a different sweetness).
Juice and zest of 1 Tahiti or Sicilian lemon . Make sure to zest only the yellow or green part, avoiding the bitterness of the white pith.
Variations : Grapefruit, Persian lime, Bahia orange, or even passion fruit work—as long as they maintain sufficient acidity. If the fruit is less acidic, add 1 teaspoon of lemon juice.
Quick Infusion Place the cream and sugar in a heavy-bottomed saucepan. Stir over low heat until the sugar disappears. When the first bubbles appear at the edges, continue stirring for 1 minute—this will allow the water to evaporate slightly and concentrate the fat, helping to reach the final point.
Aromatize off the heat . Turn off the heat, add the lemon juice and zest. The mixture becomes cloudy almost instantly: coagulation is beginning.
Rest and distribute. Wait 5 minutes for the chemical reaction to progress slowly; then, strain the cream through a fine sieve directly into small glasses or 120 ml cups. The sieve retains any lemon fibers, leaving the posset smooth as silk.
Refrigerate for at least 1 hour. Chilling completes the firming, and the cream forms into spoonfuls that tremble slightly but don’t run.
Finishing and service tips
Flavored sugar : rub the zest into the sugar before heating; the lemon essential oil perfumes the entire cream.
Crispy crust : sprinkle a little demerara sugar over the surface before freezing; it will crystallize and turn into a sweet “roof”.
Fruit compote : serve the posset with a spoonful of macerated strawberries, fresh blueberries, or diced mango – the sweetness complements the acidity.
Herbal notes : Add lemon thyme leaves to the infusion; remove before adding the juice.
Travel container : use 150 ml mason jars, close and transport in a thermal bag; the dessert lasts 48 hours in the refrigerator.
Frequently asked questions
Can I reduce the sugar? Yes. Posset depends on the lemon-to-cream ratio, not the sucrose, so you can go as low as 40g without compromising the texture; below that, the acidity becomes too pronounced.
Does it work with vegetable cream? The oat or coconut base has less casein; the cream thickens, but it doesn’t set like the original. Use 1/2 teaspoon of dissolved agar-agar to compensate.
Does freezing spoil it? Thermal shock breaks down the protein network: upon thawing, the posset separates into whey and clumps. Store in the refrigerator only.
Do I need to boil longer to thicken? No. If you reduce the heat too much, the cream will take on a caramelized flavor and may curdle when you add lemon. A brief boil is sufficient.
Lemon Posset has reinvented itself over the course of five centuries: from hot elixir to ice cream, from home remedy to elegant finishing touch for summer dinners. This contemporary recipe preserves the original minimalist spirit—few ingredients, maximum flavor—and invites you to play with aromas, fruits, herbs, and crunchy ingredients. Try it next time, watch the magic unfold in just a few minutes on the stove, and discover how natural chemistry can be as sweet as the best sugar.
