At a glance
6 small glasses, about 100ml each
EasyOne pan, no technique to learn first.
- Prep
- 10 min
- Cook
- 8 min
- Total
- 18 min
- Serves
- 6
Plus restingFour hours in the fridge, or overnight.
A posset is the oldest kind of trick: three ingredients, one pan, and a dessert that sets without eggs, gelatine, or agar. It has been made in England since at least the fifteenth century, and the mechanism was understood a long time after the recipe was.
What is actually happening
Cream is an emulsion of fat droplets in water, stabilised by casein proteins. Casein is stable at neutral pH; drop the pH below about 4.6 — which lemon juice does immediately — and the proteins lose their charge, stop repelling each other, and link into a network that traps the liquid. It is the same reaction that makes yogurt and fresh cheese, arrested at the point where it is a gel rather than a curd.
The boiling is what makes it firm rather than merely thick. Three minutes at a rolling boil drives off enough water to raise the fat and solids concentration to the point where that protein network has something to hold.
Three failures, all avoidable
Not enough fat. Below about 48% there is simply not enough to build structure, and you get lemon cream soup. Read the carton.
Not enough boiling. The most common one. Three minutes at a genuine rolling boil, not a simmer, and time it.
Juice added too hot. Straight into a boiling pan, the proteins denature and clump rather than forming an even network, and the texture goes grainy. A minute off the heat is enough.
Small glasses
Six hundred millilitres of double cream divided six ways is 100ml each, and that is the correct portion. It is one of the richest things in this section and a large bowl of it defeats people halfway down.
Something thin and crisp beside it — shortbread, a tuile, a plain biscuit. The contrast is most of the pleasure.
Ingredients
Method
5 steps
Infuse the zest while it heats
Put the cream, sugar, zest, and salt in a wide pan over a medium heat and stir until the sugar has dissolved.
Boil for exactly three minutes
Bring it to a proper rolling boil and hold it there for three minutes, stirring, watching it does not climb the pan. This concentrates it enough to set. Under-boiled posset stays loose; there is no fixing it afterwards.
Lemon juice off the heat
Take the pan off the heat, wait a minute, then stir in the juice. It will thicken visibly within seconds as the acid meets the hot cream.
Strain and pour
Pass it through a sieve to catch the zest, then pour into the glasses. Small glasses: this is very rich and 100ml is the right amount.
Four hours minimum
Cool to room temperature, then into the fridge uncovered for at least four hours. Cover once cold. Serve with something thin and crisp.
Cook's notes
- Cream at 48% fat or higher. Single cream, whipping cream, and most "light" doubles will not set, because the mechanism depends on the fat concentration.
- Ninety millilitres of juice for 600ml of cream. Less and it will not set; much more and it curdles into something grainy.
- Do not add the juice to a boiling pan. Off the heat for a minute first, or the proteins seize rather than gel.
- You will need
- Six small glasses or ramekins
- Keeps
- Three days in the fridge, covered. It cannot be frozen — it splits on thawing.
