This Keto Custard Pie is rich and creamy, with the tart sweet flavor of rhubarb. And it’s totally crustless, which means it’s easy to make and incredibly low in carbs!
If you haven’t figured this out yet, I am a rhubarb fanatic. We had a large rhubarb patch when I was growing up, and we ate it frequently whenever it was in season.
And I love re-creating some of my favorite rhubarb recipes in a keto friendly fashion. I have mastered Keto Rhubarb Crisp, and my sugar-free Strawberry Rhubarb Sauce is an absolute delight. I’ve even created a fun low carb rhubarb cocktail!
Now we can add Rhubarb Custard Pie to that list. Oooh man, is this stuff good! Just like that vintage recipe grandma used to make…except that it’s low carb and sugar-free. How can you beat that?
Why you will love this pie
If you love rhubarb, you need this keto pie recipe. The filling is creamy and rich, and provides the perfect backdrop to the stalky red vegetable. And yes, rhubarb is actually a vegetable.
I created this as a crustless pie and I’m really glad I did. For one thing, it’s incredibly easy to make this way. But it also keeps it extra low in carbs so that you can enjoy a bigger slice. And while this dessert is rich and satisfying, it’s surprisingly low in calories and fat, too!
It allows the rhubarb flavor to really shine as the star of the show. But if you’re absolutely dying for a crust, you can use my Easy Keto Pie Crust.
Ingredients you need
- Rhubarb: I recommend fresh rhubarb if you can get it. Chop the stalks into half inch pieces.
- Heavy cream: Heavy cream gives the custard pie a rich, thick consistency. You can use coconut cream for a dairy free version but it may take a little longer to bake through.
- Eggs: Custard pie requires eggs for structure. Use large eggs for this recipe.
- Sweetener: You can use your favorite sweetener for this recipe but do keep in mind that allulose will make it brown quite quickly. See the Expert Tips section for more sweetener options.
- Coconut flour: Rhubarb custard pie usually takes wheat flour to help thicken the filling. But coconut flour provides a great low carb replacement
- Pantry Staples: Vanilla, baking powder, salt.
Step by Step Directions
1. Preheat the oven to 350ºF and grease a 9-inch glass or ceramic pie pan. Spread the rhubarb in the bottom of the pan.
2. In a blender, combine the heavy cream, eggs, and sweetener. Blend briefly to combine, then add the remaining ingredients and blend until smooth.
3. Pour the mixture over the rhubarb and spread out evenly in the pan. Bake 50 to 60 minutes, until golden around the edges and the center is just barely set to the touch. If the pie is browning too quickly on top, cover with foil (shiny side up).
4. Remove and let cool completely, then refrigerate at least two hours to firm up.
I recommend using fresh rhubarb when possible. Frozen rhubarb releases more moisture during baking which can affect the consistency of the custard. If you need to use frozen rhubarb, make sure to thaw and drain it very well, and then toss with an extra tablespoon of coconut flour to absorb excess moisture.
Dying for a strawberry rhubarb custard pie? Do be aware that strawberries also add a lot of additional moisture. In this case, I might recommend adding 2 additional tablespoons of coconut flour to the batter. Or you can do as I did and simply add strawberries to the top of your pie after baking.
If you want to replace the coconut flour with almond flour, you need to triple the amount. So use ¾ cup almond flour.
Sweetener Options: The custard mostly relies on the eggs to set properly, but the sweetener you choose does make a difference. Allulose is tricky because it can make things brown too quickly but it can also make them softer. So your pie may take a lot longer to set properly after baking.
If it is browning too much, cover it with foil and reduce the heat. Then watch it carefully!
You could also use half erythritol and half of another sweetener such as stevia or monk fruit, if you wish to reduce the Swerve.
Frequently Asked Questions
Rhubarb is very keto friendly, as it has only 6g of carbs and 2.2g of fiber per cup. So you can add quite a bit of it and still not raise the carb count appreciably. It’s delicious in many recipes like Keto Rhubarb Muffins.
Traditional recipes for this pie contain plenty of flour and sugar which adds up quickly. One recipe I consulted had 46g of carbs per slice. Whereas this crustless Rhubarb Custard Pie has only 5.4g of carbs and 2.1g of fiber. So it has a net carb count of 3.3g per serving.
Custard pies need to be kept refrigerated at all times. Wrap the pie up tightly and store for up to 5 days. You can also freeze the pie for up to two months.
More recipes you’ll love…
Rhubarb Custard Pie Recipe
- 1 ¼ lb rhubarb chopped into ½ inch pieces
- 1 cup heavy cream
- 4 large eggs
- ¾ cup Swerve Confectioners (see expert tips for sweetener options)
- 1 teaspoon vanilla extract
- ¼ cup coconut flour
- 1 teaspoon baking powder
- ¼ teaspoon salt
- Preheat the oven to 350ºF and grease a 9-inch glass or ceramic pie pan. Spread the rhubarb in the bottom of the pan.
- In a blender, combine the heavy cream, eggs, and sweetener. Blend briefly to combine, then add the remaining ingredients and blend until smooth.
- Pour the mixture over the rhubarb and spread out evenly in the pan. Bake 50 to 60 minutes, until golden around the edges and the center is just barely set to the touch. If the pie is browning too quickly on top, cover with foil (shiny side up).
- Remove and let cool completely, then refrigerate at least four hours to firm up.
Absolutely the best!!!!!!!! Making it again today. Thank you for sharing this great recipe! I used my canned rhubarb, made sure to drain it well, first. LOVE IT!!!!
Sarah Davis says
What type of topping did you use in your pictures with the slice of pie topped with the sliced strawberry? I love it as it is, but for family who thinks it needs a bit more sweetness, I think it would be great topped with a creamy vanilla something. 💕 Thank you for the help!!!
Delicious! A little too sweet for me, so will cut the sweetner back a little. Always looking for a way to use my rhubarb! I added a little nutmeg to the custard. Brought back memories of the old fashioned egg custard my mom use to make when I was a girl…only wrapped around rhubarb. Thanks for this recipe.
Beth Phelps says
Hit it out of the park with this one Carolyn!!! Used first of the season fresh picked rhubarb here at our Lake house in the Interior of BC. Overwintered Rhubarb here has the most intense flavour! OMG – so good!!! Thank you for this recipe! I’ve missed having my Mom’s traditional sugar filled Rhubarb Custard Pie!
So glad you enjoyed it!
Hmmm…this was too ‘wet’ And eggy for me. Like finely scrambled eggs. Maybe more coconut flour would help?
This is AMAZING!! Thank you so much for the recipe. I will be making this over and over again.
Hello, Being Celiac I like the idea of a crustless pie, however, I would prefer to use regular or extra fine sugar. What would the replacement amount be. Thank you also for indicating that almond flour is a coconut flour substitute since I have that on hand.
Sorry, I really don’t use sugar so it’s hard for me to say. Probably about the same amount.
OH MY GOODNESS! I made this yesterday and it is sooooo good. It’s the perfect blend of sweet and tart. I may or may not have eaten a BIG slice all by myself. 😉 Thank you for this wonderful recipe!
Linda Kettner says
This is absolutely THE best! It is SO good! I’ll be making this often!!
Thank you, for this recipe!
So glad you like it!
Ok…I haven’t tried this yet, but I AM SO FREAKING HAPPY RIGHT NOW!!! I loved my grandma’s rhubarb custard pie, and I’ve missed it so much while being keto. Her recipe was 3 eggs, 1 cup sugar and flour…so there was no way I could have that now. So thank you! I’m making this tonight!! 🙂
I made this and it was delicious.
Hi, this looks delicious. If I where to use your keto pastry, should I bake it first? Thank you.
Yes, par-bake for 10 minutes, then let cool completely.
Christel Austin says
do you think a meringue would work on the top of this?
I feel like the filling might be too wet for a meringue topping.
Linnae Bosma says
Ooohhh, I can’t wait to make this! I’m currently in Killarney, Ireland on holiday but as soon as I get home and my MN rhubarb is ready I’m all in!
I have frozen rhubarb from last year. about how many cups of rhubarb is needed?
Much better to measure by weight but it’s about 3 cups.
I measured 4 cups of rhubarb to the 1.25 pounds. It was perfect.