Name: Moist rhubarb cake with pumpkin seeds
Prep time: 25 min
Cook time: 85 min
Total time: 110 min
Ingredients: 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; 63 mL sour cream (14% fat); 30 mL granulated sugar

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This rhubarb cake is made with ground pumpkin seeds and sour cream which give it a super moist, tender crumb.

Rhubarb cake with rhubarb arrangement in woven pattern

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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.

Of course, you still need a certain amount of flour, providing much-needed structure to cakes and cookies. Still, a careful swap of a portion of the flour from some ground almonds, ground hazelnuts, or other ground pumpkin seeds can lead to cakes with a very tender, moist crumb.

Another ingredient that contributes to making cakes more moist is sour cream. Sour cream provides a little acidity to cake batters, which in turn inhibits gluten formation. Less gluten means a more tender baked good that is softer, seemingly more moist.

When I was working on this recipe, I was hoping would join the ranks of my best rhubarb recipes. I wanted to make a super moist rhubarb cake that had lots of rhubarb and lots of flavour. I wanted a cake that was even better than the orange cornmeal cakes made with cornmeal and topped with rhubarb.

Rhubarb cake before baking to show how rhubarb is arranged in a pattern like it's woven

In this rhubarb cake, the weight of flour equals the weight of butter, and also the weight of sugar, which is also 150 grams (¾ cup). The new recipe is close to a "quatre quarts" (the French version of pound cake) and is a variation on the classic pound cake. We aren't exactly at a quatre quarts cake recipe here because a true quatre quarts has equal parts by weight of butter, sugar, eggs, and flour.

You'll notice in this recipe, the weight of eggs is about 100 grams, and to be a true quatre quarts, we would need to add a third egg to bring that weight up to 150 grams. I'll leave that experiment for another day... And actually this recipe is similar to the rhubarb raspberry upside-down cake batter too in the proportions, just halved.

Rhubarb pumpkin seed cake with woven rhubarb pattern arrangement

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.

Rhubarb pumpkin seed cake after baking | kitchenhealssoul.com

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.

Rhubarb pumpkin seed cake sliced into squares with woven rhubarb pattern

A few helpful resources

These are some of the baking tools I used to make this recipe:

Mini food processor: I've been using this mini KitchenAid food processor for over 5 years. It works well and you can order it from Amazon
Stand mixer: I like my KitchenAid professional stand mixer, a little more sturdy than the Artisan version, and it's available on Amazon
Square tart pan: I used a 9x9-inch tart pan with removable bottom like this one on Amazon, but this one from Paderno with a non-stick coating might be less reactive to the rhubarb (Amazon)

Substitutions for this recipe

Like with any recipe, baking substitutions can be tricky, but I have a few suggestions. I realize that the ground pumpkin seeds are a little unusual, so feel free to replace them with your favourite ground nut. Ground almonds or ground hazelnuts would be perfect here. Replace the ground pumpkin seeds with the same weight of your favourite ground nuts.

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 exactly the same.

Metal and rhubarb don't play well together

When you're baking with rhubarb keep in mind that rhubarb is quite acidic and 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 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 if 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. If the pan doesn't have a coating on it, line the bottom with parchment to avoid the rhubarb reacting with the metal.

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