Big Little Recipes

A 5-Ingredient Pudding With All the Charm of Key Lime Pie

May 22, 2018

A Big Little Recipe has the smallest-possible ingredient list and big, BIG everything else: flavor, ideas, holy-cow factor. Psst: We don't count salt or cooking fat (say, olive oil to sauté onions), since we're guessing you have those covered. Today, we're introducing Key lime pie to a old-timey pudding called posset. Spoiler: They totally hit it off.


Possets were “all the rage in the Middle Ages.” As John Ayto notes in The Diner’s Dictionary: Word Origins of Food and Drink, these British booze-set puddings reigned from then into the 19th century. But now, they’re “no longer heard of.”

Debatable, John. Debatable.

In 2010, Food52er mrslarkin wrote a recipe for Lemon Posset that over 2,000 people have favorited. And in their review, the editors swooned: “This recipe is a wonder of science. It’s the perfect thing for anyone who may be fearful of making custard.”

Basically, you boil cream with sugar, then add just-squeezed citrus juice, pour the mixture into dishes or ramekins, and chill in the fridge. There, it turns into the silkiest, thickest custard, like the easiest pudding or creamiest lemon curd or dreamiest throw-together dessert. And all without eggs.

It doesn’t have to be lemon either. You could do Meyer lemon or grapefruit or orange or tangerine or, my favorite, lime. If there’s anything sunnier, breezier, and more vacation-y—you know, even when you aren’t on vacation—than custardy Key lime pie, I need not know it.

Photo by Rocky Luten

But we should talk about that. Key lime. This petite variety is often praised for its standout flavor, but there are a few reasons why I’ll never call for it in my recipes:

  • It’s hard to tell the difference. In Kitchen Hacks by Cooks Illustrated, they did a side-by-side comparison, where tasters noted that they’re largely indistinguishable. If anything, the standard (a.k.a. Persian) limes are slightly tarter. Which I love.
  • They’re difficult to source. Bottled juice is more accessible but incomparable when it comes to taste. Fresh-squeezed always wins.
  • If you can source Key limes, you’ll need a lot. As Cooks Illustrated noted, to get 1/2 cup juice, they squeezed 3 standard limes and 20 Key limes.

Which is to say, if you’re eating a Key lime pie, be it at a restaurant or a bakery, it’s probably just a lime pie. But if you can’t tell the difference, what’s the difference?

All the streusel for me, please. Photo by Rocky Luten

This version uses standard. And, okay, it’s not a pie either. But everything else is the same. While pies rely on condensed milk and eggs for thickness and body, here it’s posset all the way. Go, posset, go!

I barely adapted mrslarkin’s recipe, swapping the citrus, and adding in zest for extra zing. And then, because streusel is the butter to my bread, the breath to my life, we’re turning the graham cracker crust into a crumble. You know when your graham cracker crust falls apart? Now that’s a good thing! I like it layered on the bottom and top because, well, why wouldn’t you? It’s not the way they would have done it back in the day. But I think you’ll love it all the same.

Have you ever tried or made posset before? Tell us about it in the comments!

29 Comments

lisa C. September 30, 2018
I made this at a friends home in Canada (I live in the US). In Canada I was able to find lactose free heavy cream and the recipe worked perfectly!
 
Erin L. July 12, 2018
Is there a non-dairy substitute for heavy cream that would work just as well (for us lactose intolerant folks)? Coconut cream?
 
Author Comment
Emma L. July 12, 2018
Hi Erin! Sorry, I haven't tested any non-dairy alternatives with this recipe so I can't say for sure how they would work. The pudding sets because of the way dairy reacts with citrus, so if you swapped in coconut cream, you'd probably need to add another ingredient to help it firm up, like gelatin.
 
lisa C. September 30, 2018
I made this at a friends home in Canada (I live in the US). In Canada I was able to find lactose free heavy cream and the recipe worked perfectly!
 
Kt4 July 1, 2018
If a Posset is defined as "British booze-set puddings", then is this recipe actually just pudding? Not being picky; just wanting to learn. To make this a 'true' Posset, can the lemon be replaced with limoncello? Or maybe part rum, part lemon juice? A booze-set pudding sounds like just the thing for July 4th celebrating!
 
Author Comment
Emma L. July 1, 2018
Hi Kt4! While alcohol was signature to classic posset recipes, citrus is more common to contemporary ones. I haven't tried incorporating alcohol into this particular formula, but I imagine that limoncello would work out well, or a mix of part juice, part booze; rum sounds great. Maybe do a half-recipe test first, to see if you like how it turns out? If you do try, I'm excited to hear how it goes.
 
Robin S. June 9, 2018
This is absolute heaven. I just put the crumble on the top only. Perfect and easy!
 
Christine June 3, 2018
I am a South Florida native, but our family moved away decades ago. We had citrus trees, including key lime, and that was my favorite pie. When Mom didn't have time to make a crust (I recall standard pastry crust, no whipped cream, meringue or green dye), she would just make the filling, pour it into cups and top it with graham cracker crumbs, yes!! My brother nicknamed it Cat Slobber, and we loved it. Posset is definitely an improvement, can't wait to try this, thank you!
 
Author Comment
Emma L. June 3, 2018
Cat Slobber! Ha!
 
Smaug June 1, 2018
If you have room, you might want to get a key lime tree; they're easy to grow, and will tolerate a few degrees of frost. They're also astoundingly prolific.
 
Smaug June 1, 2018
Sorry, this was supposed to be a comment on Syzigies' post.
 
Syzygies June 1, 2018
In California, we grow Bearss (Persian) and Kaffir limes in our backyard, and readily buy Key limes in bulk at any Mexican grocery store. Any lime shows best when tree-ripened (yellow Bearss limes from our tree make the best Moroccan "preserved lemons" I've ever made), but one can readily distinguish between varieties. The Key limes we buy do not come from Key West, while lime juice labeled from the Florida Keys is unlikely to be from Key limes. So yes, use fresh lime juice from the ripest, most appealing sources, without believing dogma that one variety is superior. At the same time, the quality of the lime is pivotal; the idea that this doesn't matter is false comfort.<br /><br />In the 1980's in New York City, a shortage of Key limes from Florida threw restaurants into a tizzy, confusing everyone's tastebuds with a barrage of Key lime desserts from other limes. Oddly, the same lime was being grown all over Mexico. While California has a strong Mexican influence, New York has a strong Caribbean influence. The Seville orange (Arancia Agria) is widely available in Hispanic markets in New York City. Besides a great marinade ingredient, they have the required acidity to substitute for Key lime juice in the classic Florida pie, and related desserts.<br />
 
Pamela D. June 1, 2018
Emma, So there isn't any booze in this posset, or the lemon one. Can you add booze as the 'acid' and make these with other flavors? Where are the booze possets?
 
Author Comment
Emma L. June 3, 2018
Where *are* the booze possets?! All the modern recipes I've come across are citrusy. I wonder if the texture is as silky and smooth? I haven't tried a boozy version of this particular formula, but now I'm really curious. I'm picturing something bourbon-y and milk punch–inspired. Or rum! If you give it a try yourself, do let me know how it goes.
 
Bella95 June 1, 2018
Wow. Talk about serendipity. Limes are usualy prohibitively expensive here but, yesterday l bought 2 bags reduced to clear AND a bottle of cream, which is something else l don't usualy buy. It's winter here so not usually the season for a Posset but l think the Gods are trying to tell me l need one.
 
Author Comment
Emma L. June 3, 2018
I think they are, too!
 
Toni May 31, 2018
Key lime anything is my favorite sweet indulgence. Would love to make this now, but only have half & half... Do you think that will work? Toni<br /><br />
 
Author Comment
Emma L. June 3, 2018
Hi Toni—I haven't tried this with half and half. With the lower fat content, it might not be as silky and smooth. But if you try it, let me know how it goes.
 
Za May 31, 2018
This is nearly the secret to my amazing passion fruit mousse. If done right you do not need gelatin or eggs to set. But you can use condensed milk and table cream (leave out the sugar) for an equally delicious dessert!
 
Shannon H. June 1, 2018
I love passion fruit anything! Any chance you will share the exact recipe?
 
Jean May 29, 2018
How is this able to set like a custard without the addition of eggs or gelatin? Is this what differentiates it from a mousse vs pudding vs panna Cotta? I'm very interested in the science of this! I can't wait to try this recipe!
 
Author Comment
Emma L. May 30, 2018
Hi Jean—the science here is really interesting! The acid alters the cream's pH and, in turn, its protein structure. It's sort of like adding lemon juice or vinegar to hot milk and making ricotta. But because cream is so much fattier than milk, instead of becoming grainy and thick, the cream becomes silky and custardy, just like pudding or panna cotta.
 
Amanda B. May 29, 2018
Any thoughts about using coconut cream instead? I can’t have dairy.
 
Author Comment
Emma L. May 30, 2018
Hi Amanda—see my reply to Jean above. Most of this recipe hinges on the reaction between acid and dairy. So if you take out the dairy, I'm not sure what would happen. I can't say for sure because I haven't tried it, but I don't believe it would work.
 
FrugalCat May 29, 2018
I'm a half hour away from the Florida Keys. Key limes are easily bought in my area. Will make again.
 
Bea May 25, 2018
Who knew? I like the simplicity of the recipe and absolutely bring on the streusel top and bottom! Let's go with some grilled pineapple too..such an easy pudding!
 
Bella95 June 1, 2018
Oooh yum. The sweetness of the grilled pineapple and the sour of the lime would be wonderful together.
 
Smaug May 23, 2018
Since you don't use key limes, or the traditional processes or ingredients of key lime pie, why even bring up the name? It seems like every sort of lime dessert made is given the "key lime pie" moniker- guessing it's because the only other lime dish with name recognition is lime jello.
 
Riddhima N. May 23, 2018
Delicious pudding, thanks for sharing.