Preheat oven to 175C/350F. Line a muffin tin with paper liners, set aside.
In a mixing bowl, use a wire whisk and whisk together cocoa powder and boiling water until a paste is formed (this blooms the chocolate, intensifying the chocolate flavour). Whisk in the cold yogurt or sour cream to cool the cocoa mixture. Whisk in the oil, egg and peppermint extract until fully incorporated. Whisk in the sugar, the sugar won't dissolve completely but it's okay.
Add in the flour, baking powder and salt and whisk gently until the dry ingredients are incorporated. Do not overmix. Use a spatula to scrape the bottom of the mixing bowl a few times to ensure all the ingredients are well-mixed together.
Scoop 1/4-cup (60ml) of batter into each liner - you will get about 8 mini cakes. Bake for 18 to 20 minutes until a skewer inserted into the center of the cake comes out clean and the top of the cake bounced back when touched gently.
Let the cake cool completely before frosting with Chocolate-Mint Swiss Meringue Frosting.
NOTES
- For more information on Dutch-processed cocoa powder and blooming of cocoa powder, click here.- To make a whole cake, grease a 6-inch round cake tin with butter and line the bottom with parchment paper. Bake for 30 to 35 minutes until a skewer inserted into the center of the cake comes out clean and the top of the cake bounced back when touched gently. Let cool completely before frosting the top and sides with the Chocolate-Mint Swiss Meringue Frosting.- If you'd like to frost the cake with chocolate ganache instead, heat 100 grams cream (minimum 30% fat) to simmering and pour over 100 grams finely chopped dark chocolate. Let sit for 5 minutes, then stir until the chocolate has melted. Add a few drops of peppermint extract if desired. Let cool until the ganache has thickened before spreading on top of cupcakes.