This Rhubarb Cake with Butter Sauce is a simple, old‑fashioned dessert that highlights rhubarb’s bright, tangy flavor in the best possible way!

A Simple Rhubarb Cake That Feels Extra Special !

There’s something special about baking with rhubarb. Its bright color and unmistakable tang mark the arrival of Spring, and when it’s paired with a simple, buttery cake and a warm vanilla butter sauce, it turns into pure comfort food!

This Rhubarb Cake with Butter Sauce is one of those timeless desserts that feels like it came straight from a handwritten recipe card tucked inside a flour‑dusted cookbook. It’s soft, lightly sweet, and studded with tender pieces of rhubarb, then finished with a pour‑over butter sauce that soaks into every bite. Simple, nostalgic, and deeply satisfying!

Why this Recipe Works

Perfect Sweet-Tart Balance – Tangy rhubarb is tempered by a lightly sweet cake and rich butter sauce, so the flavor is bright but never overpowering.

Moist, Tender Texture – As the cake bakes, the rhubarb softens and releases just enough juice to keep the crumb tender without becoming soggy.

Simple Case Base – The mild vanilla-butter cake lets the rhubarb shine instead of competing with it.

Butter Sauce Magic – I love how the warm butter sauce soaks into the cake, creating a cozy, pudding-like texture that makes every bite irresistible!

Rhubarb cake with butter sauce served warm

Ingredients You’ll Need for the Cake

2 cups Rhubarb (Chopped) – Brings that signature tart, fresh flavor and soft, jammy pockets throughout the cake.

1 1/2 cup Flour – Forms the structure of the cake while keeping the crumb tender.

1 tsp Baking Powder – Helps the cake rise so it bakes up light, not dense.

1/2 tsp Salt – Balances the sweetness and sharpens the rhubarb flavor.

1 cup Sugar – Sweetens the batter and tames the rhubarb’s tang.

1/2 cup Butter (Softened) – Adds richness and moisture, giving the cake a soft, comforting texture.

1 Egg – Binds the ingredients and adds structure.

1 tsp Vanilla – Rounds out the flavors with warmth and depth.

1/2 cup Milk – Keeps the batter moist and helps create a smooth, tender crumb.

And the Butter Sauce

1/2 cup Butter – The base of the sauce, creating richness and that irresistible melt-in texture.

1/2 cup Heavy Cream – Adds body and a silky, pourable consistency.

1 cup Sugar – Sweetens the sauce and creates a gentle caramel-like finish.

1 tsp Vanilla – Adds warmth and elevates the sauce without overpowering the cake.

Moist rhubarb cake topped with melted butter sauce

How to Make Rhubarb Cake with Butter Sauce

Preheat oven to 350 degrees. Spray a 8 x 8 pan with non-stick spray and set aside.

Cut enough rhubarb to equal 2 cups and set aside.

Whisk 1 1/2 cup flour, 1 tsp baking powder, and 1/2 tsp salt in a medium size bowl.

In separate bowl, cream together 1 cup sugar and 1/2 cup softened butter. Beat in 1 egg and 1 tsp vanilla. Stir in 1/2 cup milk.

Slowly pour the flour mixture into the wet mixture and beat together just until combined. Fold in chopped rhubarb.

Pour into prepared pan. Bake for 45-50 minutes.

Meanwhile, make the sauce by cooking 1/2 cup butter, 1/2 cup heavy cream, 1 cup sugar, and 1 tsp vanilla in a sauce pan over medium heat, stirring constantly until the sugar is dissolved and the sauce is smooth and creamy.

Pour sauce over piece of cake right before serving.

Use Fresh Rhubarb – Even though frozen rhubarb works, I recommend using fresh.

Don’t Overbake – Check the center with a toothpick and remove the cake from the oven when it comes out with moist crumbs. Overbaking dries out the cake and prevents the butter sauce from soaking in properly.

Don’t Skip the Butter Sauce – I consider the butter sauce the defining element of this dessert. It elevates a simple rhubarb cake into a rich, comforting dessert.

Make Ahead – This cake can be baked a day in advance, just make sure to cover so it doesn’t dry out.