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
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.
- 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 – Crustless or as a Crisp
FOR THE CUSTARD
- 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.