Keto Strawberry Rhubarb Upside Down Cake
Published May 9, 2020 • Updated November 22, 2025
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Two of America's classic fruit and vegetable pairing married together to form the ultimate moist, spongy strawberry rhubarb keto cake. Top with sugar-free whipped cream or ice cream for a slice of the best summertime keto dessert!
Ingredients
4 large strawberries, cut into small chunks -
3 stalks rhubarb, chopped
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2 teaspoons arrowroot powder
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3/4 cup erythritol or monk fruit sweetener, divided
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1 1/4 cup of unsalted butter, softened
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1/3 cup golden monk fruit
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1 1/2 cups almond flour
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1/4 cup coconut flour
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2 teaspoons baking powder
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1/2 teaspoon salt
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zest of one lemon
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1 teaspoon vanilla
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4 eggs
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1/3 cup sour cream or low-carb yogurt
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2 teaspoons lemon juice
Step by Step Instructions
Step by Step Instructions
Get a medium bowl
In a medium bowl, mix together rhubarb, strawberries, arrowroot powder, and the 1/4 cup erythritol or monk fruit sweetener. Set aside.
Get a large bowl
In a large bowl, whip butter with an electric mixer until light in color and fluffy (about 3-4 minutes of mixing).
Mix until fluffy
Add 1/2 cup erythritol or monk fruit sweetener and lemon zest continue mixing until fluffy. Then take out 1/4 cup of the butter mixture to use for later.
Add eggs
Add eggs, mixing in one at a time. Mix in sour cream, lemon juice and vanilla unti combined.
In a saucepan
In a saucepan over medium heat, add the 1/4 cup of reserved butter with the golden monk fruit. Whisk until bubbly (about 2-3 minutes). Remove from heat. Pour in the bottom of the bundt pan.
Bake it
Scoop cake batter on top of fruit layer and spread out evenly. Bake at 325 for about 45 minutes or until cake is firm to the touch.
Nutrition disclaimer
The nutrition information provided is an estimate and is for informational purposes only. I am a Doctor of Pharmacy (Pharm.D.); however, this content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always consult your physician or other qualified health provider before making any lifestyle changes or beginning a new nutrition program.
When strawberries and rhubarb are in season …something magical happens. They combine creating a unique flavor combination – tart and sweet. Strawberries and rhubarb are in season at the same time, so it’s only natural that we create some tasty keto dessert recipes using them.
This keto strawberry rhubarb cake is a sugar free upside down cake. The cake is spongy with a hint of lemon flavor. The crumb is moist from the strawberry rhubarb topping that is dripped over it when it is flipped upside down.
Strawberry rhubarb cake is best when you top it with homemade whipped cream or a scoop of keto ice cream. Serve a slice of cake at your next Summer party or for Mother’s Day!
Rhubarb is a vegetable that is in low in carbs. It has 1.2 net carbs per stalk. Rhubarb is keto approved.
It has a sour, bitter taste but when you contrast it with a sweet fruit like strawberries, it’s delicious!
Most berries are lower in sugar. Strawberries are a keto approved fruit since they are lower in natural sugars. They have 8.7 net carbs per cup of chopped berries.
Strawberries are in season beginning mid May to late June, so take advantage of strawberry season and make your favorite keto strawberry desserts.
This is an upside down cake recipe. You can use a regular cake pan if you want to, but I thought using a bundt pan was prettier – especially because I like to make this cake late Spring when strawberries and rhubarb are in season, so around Mother’s Day.
The size of bundt pan I use is a 10 inch pan. You can use smaller if you would like. Remember to spray coconut or avocado oil on the bundt pan before adding the batter so it slides out easy when you flip it upside down.
The directions for this sugar free cake state to whip the butter using an electric mixer until the butter is light in color and fluffy. I recommend doing this step because it creates air and volume in the butter which will yield a lighter, spongier cake.
Beat the butter with the mixer until it is fluffy and the color of the butter has changed from yellow to pale yellow or almost white. This step should take several minutes but the end result is worth it!
Absolutely loved this recipe. The lemon zest really brightened up the cake and gave it a fresh twist that paired beautifully with the rhubarb. I served it with keto vanilla ice cream and it was a total hit!
Annie, thanks for a delicious recipe! I made it for my husband’s 71st birthday & he loved it! I flubbed by adding the reserved sweetened butter to the batter (pro tip: don’t sit the sour cream & butter side-by-side). I went ahead & put in the sour cream too, praying it would turn out ok & mixed up more sweetened butter. It baked in 45 min, cooled in the pan for 30 min. When I flipped it over, only a few pieces of topping were left behind in the pan. Yum!
Can I use softened solid coconut oil instead of butter?
I haven’t tried that substitution. I think it would work. If you try it, let me know how it goes!
I have made this twice and it is absolutely delicious. However both times I have cooled the cake for a min of 45 minutes to an hour. Each time I have had the issue of the fruit/veg (I used the 1 tsp xanthan gum swap) top sticking and staying in the bundt pan, the first time taking a piece of the cake too as I flipped it. I liberally sprayed the pan with coconut oil before baking, and the second I also used some butter with no difference. Any tips or idea’s as to why this is happening? If it’s for me I don’t mind, but this is for a family member that cannot eat the traditional pineapple upside down, so I would like to present it as perfectly as possible.
Thanks,
Mel
Try round parchment sheets and use a tube pan instead of a bundt pan. If you fold the round in half to form a semi-circle, then fold 2 more times to get a cone shape, you then cut the tip about an inch up to fit over the tube in the middle of the pan. Then spray everything including the parchment with a good baking spray and it should peel off nicely once the cake has cooled. Of course, the benefit of using a tube pan also is that you can use a knife to loosen the sides before flipping. Hope this helps, and good luck.