Mojito cupcakes & matcha rice cupcakes

I've never been a huge fan of food coloring, since they serve no other purpose other than to dye a food a specific color (with the exception of red velvet, because they're rather hideous without the red hue). I've always been all about function over form, and when St. Patrick's day rolled around I found myself brainstorming ideas to concoct naturally green desserts.

The first idea I had was a mojito cupcake, which combines two green things (lime and mint). I decided to go for a traditional white cake infused with mint, with a lime curd center and a tart lime buttercream. The second idea I had was a matcha cupcake with white chocolate ganache, inspired by the green tea Kit Kat. To keep with the Asian theme of the recipe, I opted for rice flour instead of all-purpose.

Image 1. Mojito cupcakes & matcha rice cupcakes

The results were great, and I'm here to share my recipe with you.

Lime curd is best when chilled overnight, so I started with that. I used:

• 1/3 c granulated sugar
• 1 tbsp butter
• juice and zest of one lime
• 2 egg yolks

Combine the first three ingredients and heat over a double boiler. 

Image 2. Making the lime curd

Once it simmers, drizzle in the egg yolks little by little until fully incorporated. Continue to heat the mixture (I transferred it from the double boiler into the pot to expedite the process, but if you choose to do this, be sure to keep it on low heat as to prevent the egg yolks from solidifying) until thick and viscous. Refrigerate overnight.

The next step was to make the mint white cake. Traditional white cake uses only egg whites, which gives the cake its characteristic white hue. The taste can be described as somewhere in between an angel food cake and a traditional yellow cake. The ingredients that I used were:

• 1/2 c milk
• 1/4 c mint leaves, bruised
• 3/4 c all-purpose flour
• 1/2 tsp baking powder
• 1/4 tsp baking soda
• pinch salt
• 1/4 c butter
• 1/3 c granulated sugar
• 2 egg whites
• 1/4 tsp peppermint extract (I used a few drops, but it was not minty enough)

To bruise the mint leaves, simply lay them on a cutting board and beat them with the handle of your knife. Meanwhile, heat the milk in a saucepan and add the bruised mint leaves. While the milk brews, cream the butter and sugar until pale and creamy. Add the egg whites and continue to beat; you do not have to whip the whites into stiff peaks beforehand. 

The milk should be nice and minty now. Remove from the heat, stir in the peppermint extract, and allow it to cool. Once the milk is lukewarm, pour it through a mesh sieve, really squeezing the leaves so that all the minty freshness gets through. By now, the mixture will look something like this:

Image 3. Wet ingredients of mint white cake

Don't fret about the curdling. Once you add the dry ingredients (baking powder, baking soda, flour, salt), the mixture will come back together again.

Now let's check on the lime curd. It should be very thick and spreadable, almost like preserves.

Image 4. Finished lime curd

Grease a cupcake tray (or use cupcake liners). Spoon the white mint cake batter into the cupcake tray, making sure the mixture is just coating the bottom. Spoon about one teaspoon of lime curd into the center of the batter, then cover with additional batter. It should look like this:

Image 5. Filling the cupcakes with lime curd.

I made six because 24 cupcakes is way too many for two people, but if you would like to make a full dozen, of course you can double the recipe.

The matcha rice cupcakes are significantly less time-consuming, because all the ingredients can be mixed together at once:

• 3/4 c rice flour
• 1/4 c honey
• 1/4 tsp baking powder
• 1/4 tsp baking soda
• 1 egg
• 3 tbsp vegetable or canola oil
• 1 tsp matcha powder
• 6 tbsp milk

Once you get all the ingredients mixed together, the mixture will be much runnier than the white cake one. Don't worry, this is normal. Pour the batter into the cupcake tray.

Image 6. Ready for the oven

Preheat the oven to 325 degrees and bake until a knife in the center comes out clean; mine were in the oven for 20 minutes and they were cooked to perfection.

While the cupcakes are baking, you should make the lime buttercream and white chocolate ganache. The buttercream is pretty much just your traditional buttercream with some lime juice and zest:

• 1/4 c butter
• juice and zest of half a lime
• 1 c powdered sugar

Cream the butter until pale, then add juice and zest. Continue beating as you incorporate the powdered sugar little by little. Stir until just mixed, then transfer the frosting into a piping bag or a Ziploc bag.

The white chocolate ganache is a spin off of the traditional chocolate ganache. You need:

• 1/2 c white chocolate chips
• 1/2 c heavy cream

Heat the cream in a saucepan, and remove from the heat when it simmers. Pour the warm cream over the white chocolate chips immediately, and stir until all the chocolate chips are melted and the mixture is smooth with no lumps. If you are having problems with this step, microwave the mixture in 10 second increments until smooth. 

Afterwards, you want to pop this in the freezer for 5 minutes or so, because the cream won't whip to soft peaks unless it is cold. For whatever reason, white chocolate ganache won't harden on its own like regular chocolate ganache, though I suspect that this may have to do with the fact that my white chocolate chips are crappy (i.e. made of palm oil instead of cocoa butter). Once the mixture is cold, whip to soft peaks until it looks like this:

Image 7. Finished white chocolate ganache

Transfer this into a piping bag or Ziploc bag as well.

When the cupcakes are done, transfer them onto a cooling rack before you frost them, because the frosting will melt right off otherwise. Once you have piped the frosting onto the cupcakes, you can garnish them to your liking: I sprinkled some additional matcha powder onto the matcha cupcakes and topped the mojito cupcakes with additional lime zest, a lime wedge, and a mint leaf.

Image 8. Ready to eat!

The mojito one was a hit. If you only want to bake one of the two, I insist that you try that one. You won't regret it :)

Image 9. These cupcakes were devoured upon completion