Skip to Content

Rhubarb Custard – Crustless or Crisp

Rhubarb Custard – Crustless or Crisp

Rhubarb season is brief and there are so many delicious sweet and savory rhubarb dishes to make. This tangy-sweet custard can be enjoyed as a simple custard or as a rhubarb crisp. It is a rich vanilla custard over a layer of tart rhubarb and sprinkled with a nutty streusel topping. It is also easily modified to low carb without a loss in flavor.

Jump to Recipe
Rhubarb custard with low carb nut crisp topping
Rhubarb custard with low carb nut crisp topping
Rhubarb custard with no crust
Rhubarb custard with no crust

How to Purchase, Prepare and Store Rhubarb

For a little background, rhubarb is a vegetable that is used like a fruit in cooking, Rhubarb has pink to red celery-like stalks and large green leaves. The only part of the plant that is edible is the stalk; the leaves are toxic and must be removed and discarded.

The tart-flavored stalks are always served sweetened and cooked. Field-grown rhubarb is available April through July, while hothouse varieties are sold January through June.

Tips for buying and storing rhubarb

  • Select bunches of rhubarb with crisp, straight well-colored stalks. Any attached leaves should look fresh, although they should never be eaten, as they are toxic. Most stores and markets have cut off the leaves.
  • Avoid rhubarb with stalks that are turning green or have blemishes or cuts.
  • Refrigerate unwashed rhubarb in a plastic bag for 3 to 5 days.
  • Freeze fresh, cut-up rhubarb in freezer-weight plastic bags for up to 9 months.

Preparing Rhubarb

  • Trim off and discard all leaves and the ends of the stalks.
  • Remove any brown spots or coarse strings with a vegetable peeler. Wash under cold running water.
  • Cut the stalks crosswise into 1- to 2-inch pieces. Because it breaks down easily during cooking, rhubarb is usually not cut into small pieces.

How to Modify Rhubarb Desserts to Low Carb Desserts

Rhubarb custard and rhubarb custard crisp can easily be modified to be low carb recipes. In general it is a matter of switching white enriched flour to almond flour and switching pure cane sugar to a sugar substitute.

Custards include eggs, cream and sugar. Eggs and cream are staples on a low carb or keto diet so it is mostly a matter of switching out the sugar to a sugar substitute.

My favorite sugar substitute is A monkfruit blend. The monkfruit blends usually include erythritol. The flavor of the custard using this blend is very good. Some people will notice a “cooling” taste from the erythritol part of the blend. Some people also experience digestive issues with erythritol.

Even though erythritol sounds like an artificial compound, it occurs naturally in a variety of foods (e.g., grapes, mushrooms, pears and watermelon) and some fermented foods and beverages like beer, cheese, sake, soy sauce and wine. Erythritol is produced using fermentation.

Crisp toppings are also easy to modify to low carb. Instead of oats, use nuts for a nice crunch. Instead of white refined flour, use almond flour.

Cornstarch is often used to thicken fruit pies. While cornstarch is not low carb, you don’t usually use enough of it to make much of a difference.

Do Custards Require a Hot-water Bath?

While some custards do better cooked in a waterbath, this rhubarb custard dish is easy and successfully sets without a hot-water bath. It helps to use shallow gratin dishes or ramekins (2 inches deep).

Rhubarb custard with no crust

Rhubarb Custard – Crustless or as a Crisp

dorothy stainbrook
This rhubarb custard can be enjoyed on it’s own as a creamy sweet-tart dessert, or you can add a low carb nut topping to it and enjoy it as a crisp
4.82 from 11 votes
Prep Time 30 mins
Cook Time 30 mins
If making a crisp topping 45 mins
Course Dessert
Cuisine American
Servings 8
Calories 435 kcal




  • 1 lb rhubarb cut into 1/2” pieces (about 2 1/2 cups)
  • 1 1/2 cups monkfruit blend (or regular refined sugar) divided into 1 and 1/2 cup
  • 4 medium eggs
  • 1/2 cup water
  • 1 cup fluid heavy whipping cream
  • 1/4 cup butter melted
  • 2 tsp vanilla
  • 2-3 tsp orange zest or zest from 1 orange

For the Crisp Topping

  • 1 Cup almond flour
  • 1 cup brown sugar substitute I used Truvia
  • 1/2 cup nuts chopped finely (I used pecans)
  • 1/2 tsp cinnamon
  • 1/4 tsp salt
  • 4 oz unsalted butter chilled and cut into small pieces
  • 1-2 Tbsp Fresh tarragon chopped ** optional


  • Preheat oven to 260° F. Place cut-up rhubarb and 1/2 cup sugar (or sugar substitute) in bowl and microwave for 1 min. 30 seconds.
  • In a mixer, beat together until well combined the eggs, water, cream, butter, vanilla, orange zest and remaining 1 cup sugar (or sugar substitute)
  • Distribute the rhubarb evenly into 6-8 ramekins until they are about 3/4 full. I used 8 ramekins that were 5” diameter by 1 1/2 inch deep. Pour egg/cream mixture over the top of each ramekin and poke the rhubarb down to be under the custard mixture.
  • If doing custard only, bake 35 to 40 minutes. If you want a charred custard top, turn on the broiler and leave custards under the broiler for a few minutes. Be sure and watch them at this point so they do not burn.
  • If you are making the crisp: Add all ingredients except the butter to a food processor and pulse until blended. Then add the chilled butter (cut up into small chunks) to the processor and pulse for a minute or until the mixture is crumbly and well blended (like a coarse meal). If you are adding the tarragon sprinkle the chopped tarragon over the rhubarb custard mix before topping it all off with the crisp topping. Sprinkle the crisp topping over the custard in the ramekins before cooking. Check on the crisp at 30 minutes and watch until it is browned to your liking.


Calories: 435kcalCarbohydrates: 33gProtein: 9gFat: 42gSaturated Fat: 20gPolyunsaturated Fat: 3gMonounsaturated Fat: 11gTrans Fat: 1gCholesterol: 168mgSodium: 172mgPotassium: 278mgFiber: 3gSugar: 1gVitamin A: 1149IUVitamin C: 5mgCalcium: 124mgIron: 1mg
Keyword low carb crisp, rhubarb custard, rhubarb desserts
Tried this recipe?Let us know how it was!
Recipe Rating

This site uses Akismet to reduce spam. Learn how your comment data is processed.


Monday 31st of May 2021

The custard was delicious. But I cooked it in a pie pan and with the low temperature it took well over an hour and even then was not really firm. Next time I will bake it in ramekins.

dorothy stainbrook

Tuesday 1st of June 2021

Thank you for the comment Donna. I’m surprised it didn’t work as well in the pie pan. I wonder if it would have worked better if the temperature was increased to accommodate the larger surface? I’ll try it this year in a pie pan and see what happens with our stove. All stoves are a bit different....maybe yours runs a bit cooler?


Friday 28th of May 2021

One year I was given a rhubarb plant for Mother's Day. For several years I never picked it because it was green and never turned red. Finally, I found out it was of the green rhubarb variety! :)

dorothy stainbrook

Friday 28th of May 2021

Haha yes they taste pretty much the same but the green variety looks pretty awful in desserts!

Christiane Elliott

Friday 28th of May 2021

Hi, Would you know where the 38 carbs come from? It is awfully high for a low carb recipe. And Fiber was only 1 so net carbs would be 37. Thank you

dorothy stainbrook

Friday 28th of May 2021

Hi Christiane, So I went back and look at the nutrition calculator to see where the carbs were coming from. Most of them come from the sugar substitute (I tried the calculator with splenda, monkfruit and then just “sugar substitute”) 1 1/2 cups in the custard and 1/2 cup in the crisp is where the carbs are coming from. Rhubarb is quite sour so you could try and cut back on the sugar substitute, but it might not be as sweet as you want for a dessert. Here is the breakdown for the carbs using the generic word sugar substitute instead of monkfruit: 2.6 from the rhubarb, 34.25 from the sugar substitute, 3 from the almond flour, and 6 from the nuts. Everything else is something under 1. The lowest I could get it was to use a Powdered Sugar Substitute in the calculation which ended up with 33 grams per serving. I guess I would try a different fruit crisp that didn’t require so much sugar substitute to make it a sweet dessert. For me, it is still low “sugar” enough to be an occasional dessert. Another alternative is to just make the custard part and not the crisp on top. That would lower the carb content.


Monday 24th of May 2021

Picky husband loves this recipe. NuTrail makes a granola that is delightful as a topping with two grams carbs per 1/3 cup serving.

dorothy stainbrook

Monday 24th of May 2021

Oh those picky husbands! Thank you for sharing, that granola topping sounds great!


Sunday 16th of May 2021

Anyone have great savory ways to use rhubarb?

This site uses Akismet to reduce spam. Learn how your comment data is processed.