Mocha Cupcakes with Chocolate Kahlua frosting

This is the first of the three cupcake recipes from my brother's birthday. I realise they're a bit late in coming on to the blog but I've been busy with work things and haven't really had a chance to update. While I've got some free time, I thought I'd get the ball rolling.

I've made these cakes before but this is the first time I've been able to use instant espresso powder and get a true mocha flavour. It was amazing. These cakes are actually pretty simple to make and they bake with a flat top so they're extra easy to frost afterwards. The chocolate flavour is rich and deep and the espresso adds a lovely bitter coffee edge. The frosting works perfectly to create a creamy chocolatey and slightly boozey flavour that complements the cupcake perfectly.
The original recipe can still be found here at Culinography, but I halved the batch as I only needed 12 cakes and changed the measurements to metric to make things a little easier.

Ingredients
225g granulated sugar
75g unsalted butter, room temperature
1 large egg
120ml natural yogurt
110g plain flour
1/2 teaspoon baking soda
2 1/2 rounded tablespoons cocoa powder
1/2 teaspoon salt
175ml water
2 tablespoons espresso powder
1 teaspoons vanilla extract

Method
Preheat oven to 180C. Line a 12 cup muffin tin.
On medium speed, cream together the sugar, butter, and eggs until fluffy. Scrape down the sides of the bowl and mix in the yogurt.
In a separate bowl mix together the flour, baking soda, cocoa, and salt.
In a measuring cup combine the water, coffee and vanilla.
Alternate adding the dry ingredients to the butter/sugar/sour cream mixture with the coffee mixture. Mix thoroughly.
Fill the cupcake liners three-quarters full. Bake for 20-25 minutes or until a toothpick inserted in the center of cupcakes comes out clean. Remove cupcakes to wire rack and cool before frosting.

For the Kahlua Frosting I used this recipe from Group Recipes. This is a half batch with metric measurements.

Ingredients
Pinch ground cinnamon
3 tbsps boiling water
1 tbsps Kahlua
450g confectioners' sugar, sifted
40g cocoa powder
4tbsp butter, softened

Method
Place the cocoa powder In a large-ish mixing bowl & pour in the boiling water & Kahlua.
Stir with a wooden spoon or rubber spatula until the cocoa comes together into a soft mass.
Add the butter & mix with an electric mixer on lowish speed until the mixture is soft & well mixd, 30 seconds.
Stop the machine.
Add the confectioners' sugar & cinnamon & beat with the mixer on lowish speed until the sugar is incorporated, 1 min.
Increase the mixer speed to medium & beat until the frosting lightens & is fluffy, 2 mins more.
Pipe or spread onto cupcakes and enjoy!