Easy Rhubarb Custard Cake

Easy Rhubarb Custard Cake has a layer of creamy, tangy sweet custard below a fluffy yellow cake. 

Magic Rhubarb Custard Cake

Our son has recently taken an interest in magic tricks, and he’s learned one card trick that has managed to baffle and impress us all.

It involves several steps which don’t seem to follow any logic or reason, but somehow, to the delight and wonder of all of us, the correct card is always revealed in the end.

This Rhubarb Custard Cake is a magic trick of its own, made with the simplest ingredients and a few steps that will make little sense as you make it, but somehow always results in a fluffy cake with a gorgeous layer of tangy sweet rhubarb custard at the bottom. Magic.

Spatula holding a slice of rhubarb custard cake.

This recipe comes from the Amish Community Cookbook, a collection of recipes gathered from Amish and Mennonite cooks across the U.S. and Canada. It’s filled with other comfort foods I grew up with, like Amish Apple Fry Pies, Amish Chicken and Noodles, and the best Homemade Amish White Bread, but this Rhubarb Custard Cake was one I had never heard of or tried before.

Of course, I knew I could trust the Mennonites to deliver a delicious cake with little fuss. It might surprise you to find a cake mix recipe in an Amish cookbook, but sometimes Amish families need shortcuts just as much (or more!) than the rest of us.

Pink plate with a slice of rhubarb custard cake.

Here’s Why We Love this Rhubarb Cream Cake

  • It’s so fast! You can have this in the oven in about 15 minutes.
  • It uses simple (and few) ingredients. If you can get your hands on some rhubarb, you likely already have the rest of the ingredients on hand!
  • It’s so moist. The spoonable custard is rich and creamy, almost like a thick glaze for the cake.
  • It’s great for potlucks and family reunions. This fluffy, golden cake will be a hit at any gathering. The bright, tangy sweetness of rhubarb is a nice break from the usual brownies and chocolate chip cookies!

Key Ingredients

Yellow cake mix, eggs, sugar, oil, cream, and chopped rhubarb in bowls on a pink background.
  • Rhubarb – You’ll need 4 cups of chopped rhubarb, which is about 4-5 large stalks.
  • Sugar – Granulated sugar balances out the tangy rhubarb.
  • Yellow cake mix (plus the ingredients to make it) – Most call for some combination of vegetable oil, eggs, and water.
  • Heavy whipping cream- You’ll need 1 ¾ cups of cream to pour over the cake.

How to Make Old Fashioned Rhubarb Custard Cake

Before we dive in, let me just say this. Making this cake is going to feel wrong. When you start pouring cream over the top of the cake batter, an internal alarm is going to start ringing in your head.

Just this once, I’m going to tell you to ignore your baking instincts. This really works, I promise!

  1. Preheat the oven to 350 degrees. Grease and lightly flour a 9 x 13 inch cake pan.
  2. Prep the rhubarb. Place the rhubarb in a bowl and sprinkle sugar over top, giving it a stir to coat. Allow the mixture to sit while you prepare the other ingredients.
  3. Prep the cake. Prepare the cake mix according to package instructions then pour the batter into the prepared pan. 
  4. Add rhubarb and cream. Sprinkle the rhubarb and sugar mixture evenly over the top of the cake. There will be some sugary liquid at the bottom that you’ll want to add too. Pour the cream over the entire top.
  5. Place the cake in the oven and bake for 45-55 minutes, or until the top is golden brown and set and a toothpick comes out clean (the bottom third of the cake will still be wet so don’t base the toothpick test on that portion).
  6. Serve warm or chill for neater slices. You can serve this cake warm, but you’ll need a spoon! The custard will be runny (but so delicious) when warm. If you give the cake a few hours to chill in the fridge it will set up into neat slices.

Make Ahead and Storage Instructions

This rhubarb custard cake actually benefits from some chilling time, so feel free to make it up to 24 hours in advance. The cake can be stored, covered, in the fridge and will keep for 3-4 days.

You can serve the cake cold or allow it to come to room temperature before serving. You can even warm it up in the microwave. We love it both warm and cold!

Spatula holding a slice of rhubarb cream cake.

FAQs

Can I use frozen rhubarb?

You can! You don’t even have to thaw it! Just follow the instructions as usual, breaking up any rhubarb pieces that are stuck together before tossing them with the sugar.

Can I use other fruits?

I personally haven’t tried this with other fruits, but some readers have subbed half the rhubarb for strawberries or blueberries with great success. I recommend reducing the sugar by about a ¼ cup if you’re using other sweeter fruits.

Can I freeze rhubarb cream cake?

I don’t recommend freezing this cake, as the custard layer might break when thawed.

What does rhubarb taste like in a cake?

Rhubarb has a very tangy, puckery flavor that benefits from a good bit of sugar. I like to think of it as nature’s Warhead. Give fresh rhubarb a whiff and you’ll see what I mean–it hits you immediately with an earthy, tangy fresh smell.

In cakes like this one and our Rhubarb Upside Down Cake, the rhubarb is combined with sugar and cake batter to create a sweet cake with just a hint of tang.

Should rhubarb be cooked before baking?

No, you don’t need to cook the rhubarb before baking the cake.

Should you soak rhubarb before baking?

All you need to do is rinse, chop, and sprinkle sugar on the rhubarb before baking.

Fork holding a single bite of rhubarb custard cake beside a slice of cake on a pink plate.

More Rhubarb Recipes

Can’t get enough of that tangy sweet flavor? Here are a few more of our favorite rhubarb recipes!

Spatula holding a slice of rhubarb custard cake.

Easy Rhubarb Custard Cake

Yield: 15
Prep Time: 15 minutes
Cook Time: 45 minutes
Total Time: 1 hour

This creamy, fluffy rhubarb custard cake is so simple to make and is a lovely recipe for spring!

Ingredients

  • 4 cups chopped rhubarb
  • 1 cup sugar
  • 1 yellow cake mix + Ingredients for making the cake mix (eggs, oil, water)
  • 1 3/4 cups heavy whipping cream

Instructions

  1. Preheat the oven to 350 degrees. Grease and lightly flour a 9 x 13 inch cake pan.
  2. Place the rhubarb in a bowl and sprinkle sugar over top. Allow to sit while you prepare the other ingredients.
  3. Prepare the cake mix according to package instructions then pour the batter into the prepared pan. Toss together the rhubarb and sugar then sprinkle evenly on top. There will likely be some extra sugar liquid at the bottom. Make sure you get that part too.
  4. Slowly pour the cream evenly over the entire top of th ecake.
  5. Place the cake in the oven and bake for 50 minutes to 1 hour, or until top is set and a toothpick comes out clean (the bottom third of the cake will still be wet so don't base the toothpick test on that portion). Serve the cake warm with a spoon (the custard will be delicious but runny), or chill for a few hours or overnight to allow the custard to set up and slice neatly. We love the cake both warm and cold!

Notes

The cake should be stored, covered, in the fridge and will keep for 4-5 days.


Nutrition Information:

Amount Per Serving: Calories: 353Total Fat: 14gSaturated Fat: 8gCholesterol: 44mgSodium: 333mgFiber: 1gSugar: 37gProtein: 3g

Please note nutritional information for my recipes is calculated by a third party service and provided as a courtesy to my readers. For the most accurate calculation, I always recommend running the numbers yourself with the specific products you use.

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39 Comments

    1. I think if you added more cream the custard probably wouldn’t set up. You could add up to 2 cups heavy cream, but I wouldn’t go more than that.

  1. I am a rhubarb non-believer lol..someone gave us a lot of stalks and I was like..here we go..trying to find a way to use them up. I tried crisps which I hate in general. A lot of cakes suggested dicing them up and just put them in a cake was not excited either.

    This however I think will be my go to..I actually used a gluten free poundcake recipe and coconut cream to sub the heavy cream as I have allergies. I kept going for seconds…I still don’t really like rhubarb I must say like this custard layer would be better if it is just a lemony situation but…this is a great way to use them up and is a recipe I would confidently use to make people eat rhubarb without fake smiles…thank you xD.

    1. I’m glad you found a way to use rhubarb that you enjoy! Thanks for coming back to leave a review!

  2. I just took it out of the oven, looks and smells delicious, can not wait to taste it. Thank you for the easy recipe.

  3. As in an above comment, I also have been making this dessert for years. While working in memory support units, this was a go-to recipe; it utilized fresh rhubarb, (which all farm wives baked with), the residents could practically make this without supervision and then enjoyed the fragrant, delicious result!
    It’s a definite keeper!

  4. I like the idea where one reader did a 1/2 rhubarb and 1/2 strawberries. I make a strawberry/rhubarb custard pie & it call for almond extract. Any suggestions on where I could add the extract to this recipe? Thanks!

  5. I always make this cake with frozen rhubarb. Do not thaw. Just try to separate the pieces before adding it to the cake. I bang the bag on the counter before opening it. Using thawed rhubarb creates more liquid. Same goes for rhubarb pie.

  6. My MIL made this and was great. It’s almost better after being in the frig, because then the custard is.almost.like cheesecake!!!

  7. This cake was absolutely delicious. My daughter requested it for her birthday cake. She liked it because it isn’t real sweet. The rhubarb makes it tangy.

  8. The cake was done but the custard part wasn’t firm. More on the liquid side. I followed the recipe exactly, what did I do wrobg

    1. I’m sorry to hear that. The custard layer shouldn’t be liquid, but it will still have some jiggle for sure.

  9. This is one of my favorite cakes to have. I’m not a big frosting fan so the is great. I’ve used frozen rhubarb before and it turn out just fine. Made it many times like that. This cake makes me miss my grand mother. We uaed to make it together.

  10. This is such a great dessert. I often make it for potluck. It is always a hit. I have also used a lemon cake mix and substituted blueberries for half of the rhubarb. It was delicious!

  11. I have been making this cake for years. Every time I take it somewhere I’m asked for the recipe. Even people that don’t like rhubarb love this cake. I’ve made it with 1/2 rhubarb & 1/2 strawberries and another time all strawberries. A friend made it with fresh sliced peaches. Just be sure if you use another fruit besides rhubarb that you cut down on the amount of sugar.

  12. I have made this desert many times but now I’d like to make it for Easter using frozen rhubarb. Do you think using frozen rhubarb will work? Or will it be too liquidy?

  13. I was happy to see this favorite recipe of mine in print. It is a winner. I have been making it for twenty years or more and enjoyed it every time. Even though I am not Amish.

    1. It’s definitely going to be a favorite of ours from now on too! Do you ever try it with different fruits?

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