I made this rhubarb upside-down cake for the first time last year and I couldn’t resist making it again! The first time I made it, I baked it as a 9 inch round cake, but this time I wanted to see how it would turn out if miniaturized. Spoiler alert – it turned out great!
This recipe comes from one of my all time favourite blogs – Smitten Kitchen. The original instructions recommend making this cake in an oven proof skillet. You start by cooking the rhubarb topping in the skillet on the stovetop, then pile the cake batter on top of the rhubarb. You can then transfer the whole thing directly to the oven to bake. If you don’t have an oven proof skillet, the recipe also says you can make it in a 9 inch deep dish pan, or a regular depth 10 inch pan.
I don’t know why, but I love miniature desserts so much more than just having a slice of a full sized dessert. Maybe it’s just because I’m gluttonous, and when I eat a mini dessert I feel like I’m getting to eat an entire dessert rather than just a piece of one. Maybe it’s because it makes me feel like a giant feasting on something prepared by tiny humans. Either way, I just really wanted to try making mini versions of this cake in cupcake tins.
Regardless of what size pan you use, the prep work is basically the same. You start by cutting the rhubarb stalks into lengths the same width as your tin. For a large cake, this would be 9 or 10 inches long. For these mini cakes, it’s about 2 inches.
Cut your rhubarb stalks lengthwise to make ribbons. For a large cake, cut them about 1/4 inch thick. For mini ones, cut them a bit thinner, closer to 1/8 of an inch thick.
Sprinkle sugar, lemon zest and a pinch of salt into a large frying pan or ovenproof skillet. The original recipe recommends using your fingers to mix the sugar and lemon zest together to help bring out the flavour of the lemon zest. Think of the sugar acting almost like an exfoliating scrub for the lemon zest! You can do this directly in the pan, or do what I did and mix it together in a separate bowl first before sprinkling it into the pan.
Add some butter to the frying pan/skillet and set it over medium heat, stirring frequently, until the butter has melted.
Add your rhubarb ribbons to the pan and cook until the rhubarb is softened but not falling apart. When I made this as a full-sized cake last year, I only cooked the rhubarb 3 to 4 minutes. It was still relatively firm, which was okay because the cake baked in the oven for about 35 minutes.
Since mini cakes cook faster (about 12 minutes), I cooked the rhubarb a bit longer to soften it more. This was to ensure that the rhubarb wouldn’t be too firm, since it wouldn’t have the extra cook time in the oven.
Once your rhubarb is cooked, you can set it to the side and start preparing your cake batter.
In a large bowl, beat together butter, white sugar and brown sugar until light and fluffy.
Add two eggs, one at a time, beating well between each addition. Next, stir in the vanilla.
Add some baking powder, salt, cinnamon, ginger, cloves and nutmeg. Mix well to combine. Your batter will be smelling nice and spicy now!
Next, pour in a half cup of buttermilk. If you don’t have any buttermilk, you can add a half tablespoon of lemon juice to half a cup of regular milk, and let it sit for about 10 minutes before adding it your mixture.
After you add the buttermilk, your batter will have quite an unappealing curdled look to it. Not to worry though, this is expected!
Add your flour and stir it until just combined. Your batter will now be nice and smooth.
Time to revisit that rhubarb. Take your rhubarb pieces, and lay a few on the bottom of each well in your cupcake tin. (Side note: I have crazy non-stick pans, so I didn’t grease mine at all. However, if your pans tend to stick, I’d recommend greasing them lightly before adding the rhubarb.)
I made 21 mini cakes out of this recipe, but that was stretching it for the amount of batter I had. I think 18 mini cakes is a much more reasonable number to aim for.
When you cooked the rhubarb, it likely released a bunch of juice too. Spoon a little of this juice into your cupcake tin on top of the rhubarb. If you were making this as a full sized cake, you’d use all the rhubarb and the juice that came with it. For these mini cakes, I used about 3/4 of the juice that was released.
Drop a large spoonful of your prepared cake batter on top of each of your rhubarb filled cupcake tins. You can spread it around a little bit to try and smooth it out, but don’t fuss too much. It will spread out on its own while baking.
Bake the cakes at 350°F for 12-15 minutes, or until a toothpick inserted into the centre of a cake comes out clean. If baking as a full size cake, the bake time is closer to 35 minutes.
When the cakes are ready, let them cool for just a couple of minutes, before inverting them onto a wire cooling rack to cool completely. Don’t let the cakes cool in the pan for too long. You want to flip them over while they’re still really hot so they don’t stick to the pans.
If any little bits of rhubarb stay stuck in your cupcake tins, just pick them out and lay them back on top of the mini cakes.
Mini Rhubarb Upside Down Cakes
For the Topping
- 1 lb (450g) rhubarb
- 3/4 cup granulated sugar
- Zest from half a lemon
- 4 tbsp unsalted butter
- 2 pinches of salt
For the Cake
- 6 tbsp unsalted butter (softened)
- 2/3 cup brown sugar
- 1/4 cup granulated sugar
- 2 large eggs
- 1/2 tsp vanilla extract
- 2 tsp baking powder
- 1/4 tsp salt
- 1 tsp ground cinnamon
- 1/2 tsp ground ginger
- 1/8 tsp ground cloves
- 1 pinch of nutmeg
- 1/2 cup buttermilk
- 1 1/2 cups all-purpose flour
- Pre-heat your oven to 350°F.
Prepare the Topping
- Trim the rhubarb to a length that matches the width of your cake pan or cupcake tins. Slice each stalk lengthwise into ribbons. (For mini cakes, try to cut them around 1/8 inch thick. For a full size cake, cut them about 1/4 inch thick.)
- In a large frying pan or skillet, add the sugar, lemon zest, butter and salt. Cook over medium heat, stirring frequently, until the butter has melted.
- Add the rhubarb and cook until softened by not falling apart. Remove from heat and set aside.
Make the Cake Batter
- In a large bowl, beat the butter, brown sugar and granulated sugar together until light and fluffy.
- Add the eggs one at a time, beating well after each addition.
- Stir in the vanilla.
- Add the baking powder, salt, cinnamon, ginger, cloves and nutmeg, and beat to combine.
- Add the buttermilk and stir again. The mixture will look curdled and rather thin.
- Add the flour and mix until just combined.
- Arrange several pieces of cooked rhubarb into the bottom of each cupcake tin. Spoon a little of the juice from the cooked rhubarb into each tin as well (it's okay for it to be quite wet).
- Drop a large spoonful of cake batter into each cupcake tin on top of the rhubarb. You can spread it around a little bit with a spoon to flatten it out, but it doesn't have to be perfect. It will spread itself while it bakes.
- Bake mini cakes for 12-15 minutes, or until a toothpick inserted into the centre comes out clean.
- Allow the cakes to cool in the pan for just a couple of minutes, before flipping them onto a wire rack to cool. (Don't let the cakes cool down too long, you want to flip them while they're still hot so they don't stick).
- Recipe Source: Smitten Kitchen
- The original recipe suggests making this cake an oven proof skillet. Cook the rhubarb topping directly in the skillet, spoon the batter on top, then transfer the whole thing to the oven. It's a single pan cake!
- You can also make this cake in a 9 inch deep dish cake pan, or a regular 10 inch cake pan.
- If baking a large cake (not the mini cupcake sized ones) bake for 30-35 minutes.
- If you don't have buttermilk, you can add 1/2 tablespoon of lemon juice to the 1/2 cup of milk, and let it sit for 10 minutes before adding it to your batter.