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Keto Citrus Posset

This keto posset is a rich and creamy dessert that is super easy to make! Made with only three basic ingredients: heavy cream, citrus juice, and sugar substitute.

A classic posset is thickened without eggs or cornstarch; this keto version is a rich custard you can enjoy on a low-carb lifestyle.

Posset recipes can be traced back to the 14th century, during medieval times. A posset is a cross between a rich custard and a silky curd. 

They are commonly made with lemon juice for a lemon dessert, but any tart citrus fruit can be used, such as lime juice.

Although this recipe calls for the refreshing flavors of citrus, you can make it a keto lemon posset by using only lemons.

This classic dessert has a velvety, smooth, mousse-like texture and a bright flavor.

Topping this delightful dessert with your favorite fresh berries makes it a perfect refreshing dessert with a twist of citrus.

It’s the easiest way to impress dinner guests on special occasions, or anytime you want to treat yourself to a decadent dessert that won’t affect your blood sugar.

Clocking in at 2.5 g net carbs per serving, it’s a low-carb posset that allows you to enjoy a little indulgence guilt-free.

What’s more, this is a great make-ahead classic British dessert that is easy to customize.

Keto Citrus Posset, A Citrus Custard

Easy keto citrus custard
Easy keto citrus custard

Simple ingredients come together for a delectable keto dessert you will be proud to serve.

Converting a classic lemon syllabub with keto-approved ingredients proved to be a winning recipe.

I quickly realized that only a handful of ingredients are needed to create a rich, creamy custard and that traditional thickeners like eggs are unnecessary.

These two things reassured me that a keto citrus posset was probably very possible.

The whole thing sounded pretty amazing, and I got over the strange name rather quickly once I started to research the recipe a little deeper.

But how does a posset not need any thickeners to make the custard? I mean, it doesn’t even use egg yolks! Well, it seems it’s just a little basic science at work.

In my quest to see if I could genuinely convert a classic posset into a keto-friendly dessert, I came across Cook’s Illustrated article.

This is a summary of what the article explained:

When acid is introduced to milk, or when milk naturally sours over time, the change in pH leads to the loss of negative charge in the milk’s casein proteins, which typically keeps them separated. Instead, they form clusters, causing the milk to become grainy or curdled.

In the case of cream, which has a higher viscosity due to its lower water content and higher fat content (at least 36 percent fat compared to whole milk’s 3.25 percent), the outcome is different.

The fat in cream outweighs the casein proteins by a ratio of 10 to 1 (compared to being roughly equal in milk), thereby interfering with the proteins’ ability to form tight curds.

Consequently, a smooth, creamy consistency develops rather than a grainy one. Additionally, heating the cream for posset has an impact by causing the whey proteins in the dairy to unwind and attach themselves to the casein molecules, thereby aiding in stabilizing the gelled liquid.

I must say, Cook’s Illustrated did an excellent job explaining the science behind this classic dessert, don’t you think?

Ingredients & Tools Needed

Keto citrus custard posset

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The following are the ingredients and tools you’ll need to make this simple dessert that can be enjoyed on a keto diet. Note that the full printable recipe card is at the bottom of the page.

Optional Topping

  • Lemon zest
  • Lime zest
  • Fresh blueberries


How To Make A Keto Posset (Custard)

low-carb posset being made
low-carb posset being made

When I realized that keto citrus custard (posset) uses heavy whipping cream rather than milk for the custard, I instinctively felt that a keto option was not only possible but about to step into my life and make things just a little more magical.

The basis of this type of custard is straightforward. Just heat the heavy whipping cream and granulated sugar substitute until they lightly boil, and the sweetener completely dissolves.

Once the mixture reduces, you can add your citrus of choice and allow the mixture to congeal into a velvety smooth keto citrus custard masterpiece.

Most of the posset recipes I researched use lemon juice. You can basically use any form of citrus that is sour enough.

So, true to my nature, I thought I would experiment by using a combination of three citrus flavors. This is why I added orange extract to my recipe rather than a couple of tablespoons of orange juice.

I knew that I would have to get the cream, citrus juice, and sugar substitute ratios perfect.

Allowing the cream and sugar substitute to reduce sufficiently before adding the citrus juice would also prove vital to the success of converting the posset to be keto-friendly.

If you love the flavor of citrus, Perhaps you would also enjoy my Keto Lemon Curd Pied and my Keto Lemon Cookies.

Best Sugar-Substitute Options For This Recipe

As far as the best sweeteners for this sugar-free dessert, I recommend the use of Lakanto’s granulated sugar substitute. It’s their erythritol and monk fruit sweetener that is as close to sugar as it gets.

Having said that, you can also use the brand Swerve, which is an erythritol blend. Similar to Lakanto, it uses sugar alcohols and has a 0% impact on blood sugar.

If you prefer to use a stevia-based sweetener, you could also use the stevia- and erythritol-based brand Pyure. However, since this is a much sweeter option, be sure to reduce the amount called for in the recipe by half.

Lastly, if you can’t easily find a more natural sugar substitute, you can also use Splenda with good success.

I know not everyone would agree with me here, and I respect that, but in my book, it’s still better than regular sugar.

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It’s what keeps this girl encouraged.

Do you know what goes fabulously with this recipe? My favorite nootropic coffee supplement. It’s a cup of coffee that gives you clean energy and pairs well with this recipe.

Grab Our Books!

In case you don’t know, I have authored two books for you, Essential Keto Bread and Essential Keto Desserts, both inspired by your requests over the years.

I pray these keto cookbooks will help make keto a delicious breeze for you.

Join Our Jesus And Keto Movement 

Looking for an online support system to help you stay on keto? As a family, we came to the keto diet, looking at it from a Christian perspective. As believers, we live our lives supported by God’s grace.

So when the Holy Spirit led us to combine our Christian faith and the keto diet, we did so in hopes of finding lasting transformation.

When we followed the Holy Spirit’s prompting, we got on the path to real transformation. 

Knowing firsthand the benefits of this decision, we have created a closed Christian group that is using the keto diet to transform their lives. 

We invite you to join our Private Facebook Group and see if it’s not the key you have been missing.

Be sure to request our FREE Jesus and Keto E-Book (First 7 days). We hope it blesses you.

Fittoservegroup Keto App

Fit To Serve Group App

Looking for a fast way to access our keto recipes? We’ve got you covered. There’s an app for that. Yup, there’s a Fit To Serve Group App and it’s going to make your keto diet a delicious breeze!

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Get the Fit to Serve Group App for easy-to-follow keto recipes made with easy-to-source ingredients. 

The app is loaded with hundreds of yummy recipes for breakfast, lunch, dinner, snacks, and even desserts!

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Keto citrus custard posset

Keto Citrus Posset

Yield: 4
Prep Time: 10 minutes
Cook Time: 6 hours
Total Time: 6 hours 10 minutes

This keto citrus posset is a citrus custard recipe. made easily with only 3 ingredients, It's a keto-friendly option for the classic British dessert.


Keto Citrus Posset

Optional Topping

  • 1 teaspoon of lemon zest
  • 1 teaspoon of lime zest
  • 1/2 cup of fresh blueberries


  1. Boil the heavy cream and sugar substitute for 6 minutes, stirring to prevent the mixture from boiling over.
  2. Take the cream mixture off the stove, add the citrus juice, orange extract, and sea salt, and mix well.
  3. Pour the keto posset into four 1/2-cup ramekins.
  4. Chill for at least 6 hours or overnight to allow the mixture to fully thicken.
  5. Store the leftovers in the refrigerator for up to five days.


  1. Top with lemon and lime rind and fresh blueberries.
Nutrition Information:
Yield: 4 Serving Size: 1/2 cup
Amount Per Serving: Calories: 264Total Fat: 27.9gSaturated Fat: 17.5gCholesterol: 103mgSodium: 33mgCarbohydrates: 2.6gNet Carbohydrates: 2.5gFiber: .1gSugar: .6gProtein: 1.7g

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