Lemon Posset

While writing a profile on lemons, I asked a group of food writers, “What’s the quintessential lemon dessert?”  As one would imagine, all the classics were suggested–lemon bars, lemon meringue pie, lemon pound cake, etc.  But it was a writer from the UK who got my attention with a suggestion of lemon posset. I had never heard of it and immediately set out to learn more.

In it’s earliest form, posset was a popular medieval drink made from warmed sweetened milk that had been curdled with wine, ale or some other acidic agent. It may be difficult to understand the appeal, but eventually the milk was replaced by cream, and the ale and wine by lemon juice. What resulted was a rather luxurious dessert more akin to a custard than a nog. Posset fell from favor in the early 19th century, upstaged by egg custards and something with the equally peculiar name of syllabub, but has enjoyed a resurgence in recent years.

The expression “easy peasy, lemon squeezy” may have been the slogan of an old British detergent, but it is a fitting description of lemon posset.  Few desserts are easier. The Wall Street Journal calls it a “pudding that practically makes itself.” Three simple ingredients–cream, sugar, and lemon juice–combine and through some magical food alchemy transform one another into a thick, rich, custardy dessert. It’s enough to capture the fascination of your inner food geek.

HOW IT WORKS

Remember Little Miss Muffet’s curds and whey? Well, when hot milk mixes with an acid, its two main proteins, casein and whey, react very differently. Casein begins to coagulate forming a solid mass, while the whey separates into a watery liquid. (Think cottage cheese.) It may not sound like much of a dessert by today’s standards, but when that same acid is mixed with heavy cream, the extra fat cells block the casein from forming large curds.  Then, when the mixture has had sufficient time to cool, it sets into a custard-like texture without the aid of eggs or gelatin.

All food chemistry aside, what about the taste?  Is lemon posset the quintessential lemon dessert?  You’ll have to decide for yourself, but it’s fair to say that posset is to lemons what key lime pie is to key limes.  Nothing short of lemon curd could pack more lemon flavor.

THE BASIC METHOD

Writing in The GuardianFelicity Cloake appears to have perfected lemon posset.  So I began working from her recipe. The biggest problem from the outset was that folks in the  UK use double cream, which has somewhere between 43 and 48% milk fat and is all but non-existent in the U.S.  In order to stop the casein from curdling into chunks, you need at least 25% milk fat. Heavy whipping cream is between 36-38% fat–more than enough to do the trick.

Most recipes call for mixing cream and caster sugar, heating it to a boil, and then adding the lemon juice, but like Cloake, I found I got a smoother texture by heating the lemon juice and sugar together to create something of a simple sugar.  This method requires two sauce pans–one for the syrup and one for the milk, but it also allows me to use granulated sugar in place of caster (aka “superfine”) sugar; something I never seem to have on hand.

The set was inconsistent in early batches. Some would firm like a well-made custard, while others were loose like packaged pudding or greek yogurt; a problem I feared rooted back to the percentage of milk fat. I eventually realized that the longer I simmered the heavy cream, the firmer the set. Those extra minutes on the stove helped to reduce the liquid.  Cooling the posset 20-30 minutes on the counter before refrigerating also helped.

Lemon Posset

Print Recipe
Two lemons should produce enough juice, but depending on the season, you may want to have a third lemon handy, just in case. Be sure to use heavy whipping cream and not regular whipping cream, light cream or half and half.Ingredients
Course Dessert
Cook Time 10 mins
Total Time 4 hrs 10 mins
Servings 4

Ingredients

  • 2-3 lemons preferable unwaxed
  • cup (125g) sugar
  • 2 cups (475ml) heavy cream

Instructions

  • Rinse, dry and zest one of the lemon. Slice and squeeze the zested lemon plus one other and measure 3 ounces (90ml) of lemon juice. If needed, use the third lemon.
  • Combine the zest, juice and sugar in a small sauce pan and stir until blended. Cook over medium-low heat, until the sugar has completely dissolved, stirring constantly. Liquid should be transparent. Be sure to scrape down any sugar that collects on the side of the pan. Remove from the heat and cover to keep warm.
  • In a heavy medium sauce pan, gently bring the cream to a boil over a low heat stirring frequently to avoiding scalding and skimming. Allow to simmer for 3-4 minutes string occasionally.
  • Remove from heat, and gently whisk the lemon syrup into the cream until well blended.
  • Using a fine mesh strainer, strain the cream mixture into a bowl or glass measuring cup with enough capacity for 3 cups.
  • Using a ladle or the spout of the measuring cup, divide the posset evenly into four custard dishes. Allow to cool on the countertop for 20-30 minutes, then refrigerate for 2-4 hours until firmly set. 
  • For longer storage, cover custard dishes with plastic wrap. Lemon posset is best if eaten within 48 hours.