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This is a soft, old-fashioned Rhubarb Cake with Butter Sauce: a simple one-bowl cake to stir together and bake in a 9 x 13 pan. This is perfect for a potluck or picnic.

Rhubarb Cake with Butter Sauce
Tangy Rhubarb Cake becomes completely irresistible when paired with the sweet Butter Cream Sauce. This cake is a twist on a classic Christmas dessert, cranberry cake with butter sauce.
I’ve updated it for spring and substituted rhubarb for the cranberries. It works so well, as both cranberries and rhubarb are tart and pair well with the butter sauce.
How To Make An Old Fashioned Rhubarb Cake
This is an egg-less cake which makes it super easy to make in one bowl. First, you’ll sift all the dry ingredients together. They are just the basics: flour, sugar, baking powder, and salt.
To that mixture you’ll gently stir in the milk, melted butter and diced rhubarb. Pour into a pan and bake.

This is seriously the easiest dessert. It’s just as fast as using a cake mix and doesn’t require and special ingredients (other than rhubarb, of course.)
The Rhubarb Cake is perfect for last minute company or anytime you want to bring a dessert somewhere.
The lack of eggs in this cake makes it especially tender and I love that. Be careful not to over bake it as it will be dry. Don’t worry though, a healthy dose of butter sauce will fix it.

How To Make Butter Sauce
Butter sauce is just butter, heavy cream and granulated sugar – and it is oh, so delicious when poured warm on cake. Think of it as a superior frosting since frosting is just sugar and butter too.
In a small saucepan, melt the butter, stir in the heavy cream and sugar, bring to a boil and boil for 1 minute.
Ta da, magic butter sauce that is perfect over cake.
In addition to seeing this butter sauce over cranberry cake, I’ve also seen it served over a Pecan Praline Cake and a Warm Gingerbread Cake.

More Rhubarb Recipes
Both my family and my reader’s love rhubarb recipes. If you’re looking for ways to use up extra rhubarb, check out one of my other rhubarb recipes.
- Rhubarb Bars
- Rhubarb Coffee Cake
- Rhubarb Crunch
- Strawberry Rhubarb Crisp
- Rhubarb Sauce
- Old Fashioned Rhubarb Custard Pie
- Strawberry Rhubarb Cobbler
Can I Freeze Rhubarb?
Rhubarb season is short, but never fear, you can use freeze rhubarb and use it throughout the year without any issues at all. You can also purchase frozen rhubarb at most grocery stores.
To use frozen rhubarb: thaw the rhubarb first and let any excess liquid drain off. Don’t squeeze any liquid out, just drain what naturally thaws out of the rhubarb.

Rhubarb Cake with Butter Sauce
Ingredients
For the cake
- 4 cups all-purpose flour
- 2 cups granulated sugar
- 4 teaspoons baking powder
- 1/2 teaspoon salt
- 4 cups rhubarb diced (see note below about using frozen rhubarb)
- 2 cups milk
- 6 tablespoons butter melted
For the butter sauce
- 1/2 cup 1 stick butter
- 1 cup sugar
- 3/4 cup heavy cream
Instructions
- Preheat oven to 350° F. In a large bowl, whisk together the flour, sugar, baking powder and salt. Add the diced rhubarb, milk and melted butter. Stir just until combined.
- Pour the batter into a greased 9 x 13 inch baking pan. Bake for 45 minutes or until a toothpick inserted comes out clean.
- Remove from the oven and cool
- To make the butter sauce, combine the butter sugar and cream in a heavy saucepan. Bring to a boil over medium heat and boil for 1 minute stirring frequently. Remove from heat and let cool slightly.
- To serve, cut pieces of cake and serve with a generous amount of warm butter sauce. The sauce can be gently reheated on the stove or in the microwave if necessary.
Notes
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
{originally published 4/20/19 – recipe notes and photos updated 5/6/21}
















I thought I’d love this, but all I taste is sweetness — not rhubarb.
Sorry to hear that it wasn’t a hit with you, Jody.
This recipe is great. The butter sauce makes it. I use 2 round cake pans. One to keep at home and one to share at work.
I’m thrilled that you are enjoying the cake, Kathy.
I just made this and I was kind of disappointed. I was hoping for something a little lighter on the cake side. It tasted like flour.
I’m sorry to hear that, Tiffany. I don’t notice a pronounced flour flavor in this cake. Did you by chance substitute any ingredients?
For the butter sauce, is it granulated or powdered sugar?
That’s regular granulated sugar, Linda. Enjoy!
Can I cut this recipe in half?
That should work fine, Patsi.
Just whipped this up. In the oven as I type. There was no pouring batter into the pan. It was very stiff. Then needed to spread it out into the 9×13 pan. Fingers crossed it works out, time will tell!
I hope you love it, Patty!
Was it to be a very stiff batter? Well I liked it…it tasted like a shortcake I make for strawberries…I’m thinking if I make this again…I will pour the butter sauce all over the cake when it comes out of the oven!
This recipe screams Summer! I especially love the butter sauce!
Oh yum!!! This looks so amazing.
Such an incredible cake!! I would love a slice of this!
Rhubarb is such a favorite of mine and totally takes me back to my childhood. This cake sounds amazing and I can’t wait to take my first bite!
This sounds so decadent; that butter sauce makes the dish! Yum!
Do you use salted or unsalted butter ?
I use salted butter, Stephanie.