Moist Rhubarb Cake

This moist rhubarb cake is made with ground pumpkin seeds and sour cream, creating a tender cake crumb with a nutty flavour that pairs beautifully with tart rhubarb.

Sometimes, the secret to a moist cake can be less flour, or replacing a portion of the flour with a flour alternative, like a starch (cornstarch, for example) or even ground nuts. The ground nuts add texture to the cake crumb and lighten it in a way that flour can't achieve.

A careful swap of a portion of the flour with some ground almonds, ground hazelnuts, or ground pumpkin seeds can lead to cakes with a very tender, moist crumb and a light texture. This works beautifully in these rhubarb sour cream muffins and the gorgeous rhubarb upside-down cake, made with ground almonds, and in the recipe below with pumpkin seeds!

What You Need

• rhubarb—use fresh or frozen rhubarb. I use chopped rhubarb in the cake and sliced rhubarb for the top
• pumpkin seeds—use raw, untoasted pumpkin seeds
• butter—I bake with unsalted butter. If using salted, you may want to add less salt to the cake to compensate
• sugar—I used granulated sugar, but brown sugar will also work great
• eggs—I always bake with large eggs. Using a different size of eggs may affect the texture
• leavening—we are using baking powder in this cake, not baking soda. Please read about the difference between baking powder and baking soda if you are unsure
• sour cream provides a slight acidity to cake batters, which in turn inhibits gluten formation. Reducing gluten results in more tender baked goods that are softer and moister. Please use full-fat sour cream (14 % fat) for the best cake texture
• salt—I bake with Diamond Crystal Fine Kosher salt. If using regular table salt, add half the amount or the cake may be too salty

Please see the recipe card for the exact ingredients and quantities.

Substitutions And Variations

Like with any recipe, baking substitutions can be tricky, but I have a few suggestions:

• Nuts—I realize that the ground pumpkin seeds are a little unusual, so feel free to replace them with your favourite ground nut or even sunflower seeds. Ground almonds or ground hazelnuts would be perfect here. Pistachios would be excellent! Replace the ground pumpkin seeds with the same weight.
• Greek yogurt—for the sour cream, you can replace it with the same volume of full-fat plain Greek yogurt. Low-fat would probably work too, but your recipe will have less fat, and I can't guarantee that it will work out the same.

How To Make A Moist Rhubarb Cake

Step 1—Combine all the dry ingredients, including the pumpkin seeds in the bowl of a food processor fitted with the metal S-blade (image 1). Process the mixture until the pumpkin seeds are fairly finely ground (image 2).

Step 2—Cream the butter with the sugar until very light (image 3) before adding the eggs (one at a time) and vanilla (image 4). Whip the mixture until it is very light and fluffy (image 5). You want to incorporate a lot of air!

Note: When you are taking away flour from a recipe, even if it's a fraction that is removed, the key to this making the cake light and fluffy is beating the butter and sugar for a very long time (like 4 minutes), and then beating in the eggs, one at a time, and then 4 minutes more after they are all added. The resulting batter at this stage is emulsified nicely and extremely light and fluffy, resembling soft whipped cream. Don't even bother moving forward with the recipe until you achieve that texture.

Step 3—Add half the dry ingredients to the mixer (image 6) and stir them in before adding the sour cream (image 7), then mix in the last of the dry ingredients to create a thick batter (image 8). Stir in the chopped rhubarb (image 9).

Step 4—Transfer the rhubarb sour cream cake batter to a prepared square cake pan (mine is non-stick, so I buttered it then lined it with parchment paper, leaving an overhang). Arrange logs of rhubarb decoratively in a cross-hatch pattern or weave, sprinkle generously with sugar (image 10), and bake until golden brown (image 11). Use a cake tester to make sure it's done.

Tip—make sure the logs of rhubarb on the top aren't too thin because they become thinner and a little tough to bite through when baked.

The resulting rhubarb cake is very moist and full of rhubarb chunks that go so well in this sweet, nutty cake. It's absolutely addictive and the perfect cake to bake with rhubarb this season. This rhubarb cake is quite different than the rhubarb pudding cake (with rhubarb compote baked under a thick layer of cake) and the orange cake made with cornmeal and topped with rhubarb.

Baking With Rhubarb Tip: Metal And Rhubarb Don't Play Well Together

When you're baking with rhubarb, keep in mind that rhubarb is quite acidic. You need to consider the material of your cake pan or bakeware, especially for recipes where the rhubarb may come into direct contact with the pan. I used a square 9-inch tart pan with a removable bottom, but I found the rhubarb chunks in the cake discoloured the stainless steel finish in places. So even though I used a stainless steel pan for this recipe, it might be more appropriate to bake it in a coated stainless steel, ceramic, or even glass pan to avoid discolouring your pan. You may have to adjust the baking time accordingly since glass, for example, is insulating and slower to heat up, which means your cake will take a little longer to bake.

Regardless of whether your pan has a special coating on it (ceramic or non-stick) or not, be sure to take the time to prepare the pan before baking: grease the pan, and dust the sides with flour or line with parchment. If the pan doesn't have a coating on it, line the bottom with parchment with an overhang to avoid the rhubarb reacting with the metal as much as possible.

Serving Suggestions

I like to serve this cake plain, but also with lightly-sweetened whipped cream. This maple whipped cream would also be lovely paired with this rhubarb cake. And you can also serve it à la mode with a scoop of cardamom ice cream.

Other Rhubarb Recipes

I love to bake with rhubarb. The tart flavour of rhubarb allows it to pair nicely in sweet baked goods like these rhubarb recipes:

If you tried this recipe for the best moist rhubarb cake (or any other recipe on my website), please leave a ⭐ star rating and let me know how it went in the comments below. I love hearing from you!

📖 Recipe

Moist Rhubarb Cake with Pumpkin Seeds

AuthorAuthor : Janice Lawandi

This rhubarb pumpkin seed cake reminds me of a giant financier, it's nutty and moist, and full of rhubarb.

5 from 1 vote

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Prep Time 25 minutes mins

Cook Time 1 hour hr 25 minutes mins

Total Time 1 hour hr 50 minutes mins

Course Dessert

Cuisine American, French

Servings 9 pieces

Calories 367 kcal

Equipment

• ▢
  9x9-inch pan
• ▢
  Mini processor
• ▢
  5-quart KitchenAid Artisan mixer
• ▢
  Mini offset

Need measurements in CUPSUse the button options below to switch from Metric to US measurements! It's that easy!

Ingredients

 

MetricUS

 

0.5x1x2x3x

• ▢ 450 grams fresh rhubarb washed and trimmed
• ▢ 156 grams bleached all-purpose flour
• ▢ 108 grams pumpkin seeds
• ▢ 5 mL baking powder
• ▢ 3.75 mL Diamond Crystal fine kosher salt
• ▢ 153 grams unsalted butter room temperature
• ▢ 150 grams granulated sugar
• ▢ 2 large egg(s)
• ▢ 5 mL pure vanilla extract
• ▢ 65 mL sour cream (14% fat)
• ▢ 30 mL granulated sugar

Instructions

 

• Preheat the oven to 350 °F (175 °C). Butter a 9x9-inch (23x23-cm) square pan (preferably non-reactive and non-stick). Line with parchment paper leaving an overhang. Set aside.
• Slice rhubarb in half, lengthwise (or even in quarters for thicker stalks of rhubarb) and then into 2 ½" pieces. Select about 27–36 of the prettiest and set them aside for the top of the cake. Chop the rest into ½" pieces. Set aside.
• In a food processor (like this KitchenAid on Amazon), pulse together the flour, pumpkin seeds, baking powder, and salt until the seeds are finely ground and the dry ingredients are evenly mixed.
• In the bowl of a stand mixer fitted with the paddle attachment (like this KitchenAid on Amazon), cream together the butter and sugar, then beat them together on medium-high speed for a full 4 minutes, until light and fluffy. Scrape down the bowl as needed with a spatula. Add the eggs, one at a time, beating well between each addition. Then add the vanilla, and beat the mixture again for another 4 minutes on medium-high until it's very pale, light (like soft whipped cream).
• With the mixer on low, add half the dry ingredients, mix them in, then add the sour cream. Scrape down the bowl again, then add the rest of the dry ingredients, and stir just to combine. Take the bowl off the stand, then fold in the ½" rhubarb pieces with a spatula. The batter will be very thick.
• Spoon the batter into the prepared pan, smearing and pressing it into the corners and edges of the pan. Then arrange the reserved sticks of rhubarb on the top into a pattern (see picture). Sprinkle with 2 tablespoon granulated sugar. If you are using a pan with a removable bottom, place it on a baking sheet.
• Bake the cake until the edges are nicely browned, and a skewer inserted into the middle comes out clean. This takes about an hour (more or less).
• Let cool before serving. Unmold after about 20 minutes. Cut into squares once cooled.

Notes

• This recipe calls for Diamond Crystal fine Kosher salt. If using regular table salt, add half the amount or the recipe may be too salty!
• You can replace the sour cream with full-fat Greek yogurt (around 9 % fat or more).
• Substitute light brown sugar for granulated sugar in the cake batter (same weight).
• Use ground almonds, hazelnuts, or pistachios in place of pumpkin seeds (same weight). Or you can use sunflower seeds if you'd like to keep the cake nut-free.
• Beware of baking in aluminum pans: the rhubarb is acidic and can cause the pan to blacken in places if the aluminum pan is uncoated (or not anodized). 

Nutrition

Calories: 367kcalCarbohydrates: 37gProtein: 7gFat: 22gSaturated Fat: 11gPolyunsaturated Fat: 3gMonounsaturated Fat: 6gTrans Fat: 1gCholesterol: 77mgSodium: 221mgPotassium: 343mgFiber: 2gSugar: 21gVitamin A: 574IUVitamin C: 4mgCalcium: 92mgIron: 2mg

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This rhubarb cake recipe was adapted from the April 2015 issue of Bon Appétit magazine, page 66. You can find a version online here: Bon Appétit recipe,