This one-bowl rhubarb upside down cake has a butterscotch vibe without any actual caramel-making. Instead, you simply start out with brown sugar, which gives it a lovely caramel-ish flavor. The bottom of the pan gets coated in brown sugar, then rhubarb slices, then batter. The rhubarb and brown sugar become super syrupy, soaking slightly into the crust of the cake after inverting. We’re sacrificing some of rhubarb’s bright pink hue in favor of a deep, caramel flavor. And that’s a trade I’ll happily make any day!

Jump to the recipe to hit the ground running, or read on if you want to learn a little more about what makes this recipe unique.

Rhubarb upside down cake specs

1. One-bowl!

My pet peeve is a one-bowl recipe that sacrifices quality for efficiency. But this recipe is not one of those. Instead of mixing the brown sugar topping in a separate bowl, my recipe has a helpful reminder not to wash that bowl. Instead, you should save it for making the batter. Who cares if there are a few bits of oil and brown sugar?

And instead of sifting your ingredients into a separate bowl, you will sift them right on top. The one caveat is to be very careful not to over-mix at this point. Adding the wet ingredients on top of the dry ingredients makes everything come together more easily. Adding the dry ingredients on top means you need to be more efficient with your mixing and stop as soon as there are no dry pockets of flour (even if it’s still a little lumpy).

2. Oil instead of butter = easier to store in the fridge

This recipe uses oil instead of butter, and that’s for a practical reason:

Ideally, baked goods are consumed the day they are made, but if you have to store one, the refrigerator is one of the worst places you could choose. Flour-based baked goods stale much more quickly in the cold environment of the fridge.

But with a fruit-based cake, you really need to store it in the fridge if you’re going to keep it longer than a few hours before enjoying. This creates quite the dilemma!

So to help fridge-proof it, we need to use oil instead of butter in the batter. Butter-based baked goods tend to stale more dramatically and more quickly when stored in the refrigerator. Using oil doesn’t mean we’re preventing staling completely, but it does buy us a day or two.

I’ve enjoyed this cake straight from the fridge the next day without any noticeable staling. If you notice it has staled slightly, you can always pop it in the microwave for 30 seconds or so.

3. Super forgiving design

For this recipe, you really don’t need to arrange the rhubarb slices carefully across the pan. It’s a pretty rustic cake, so it looks great whether your slices are scattered or carefully arranged in concentric circles.

If you’re going to scatter them, I recommend slicing straight across into “C” shapes, which will nest together more easily into a single layer. That single layer specified in the recipe is very important—you don’t want any rhubarb pieces floating away and getting lost in the batter, and you want the rhubarb to cook through at the right rate. You just want one 1/2-inch layer of rhubarb pieces.

4. Can be made completely dairy-free

This recipe is already halfway to dairy-free, and you can absolutely get away with using an equal amount of unsweetened, plain soy milk in place of the cow’s milk. I’ve made it dairy-free many times using soy milk as a substitute.

I’ve never tried substituting vegan “eggs” in place of the chicken eggs, so if you want to make it totally plant-based, I can’t guarantee it would work. So I wouldn’t give that a try unless you are up for a risky experiment that may or may not work out (and if it doesn’t work out, you’ve been warned, so please don’t rate it 1 star 😇).

Hope you enjoy this recipe! And if you’re looking for more ways to use up rhubarb, I’ve got a couple more.

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