ONE BOWL CHOCOLATE CUPCAKES

1. Preheat the oven to 350°f / 180°c. Line a muffin pan with cupcake liners (This recipe made 14 to 16 cupcakes so you may need two pans, or you can bake them separately).
2. In a large bowl, whisk together the flour, sugar, cocoa, espresso powder, salt, baking soda, and baking powder. Add the eggs, yolk, vanilla bean paste, oil, and milk, and mix to combine well. Add the boiling water and whisk until incorporated.
3. Scoop about ¼ cup plus 2 Tbsp of batter into each liner using a cookie scoop (I have a ¼ cup scoop and a 2 Tbsp, or you could use a quarter cup measure).
4. Bake the cupcakes for 19 to 20 minutes, or until they spring back when touched, or a toothpick inserted into the cupcake comes out clean.
5. Cool on a wire rack.

DARK CHOCOLATE SOUR CREAM GANACHE

1. Place the sour cream and chopped chocolate into a heat proof bowl, and mix to combine.
2. Microwave for 30 second intervals, stirring well between each interval (it will likely take a minute, but watch carefully). Once the chocolate is melted, switch to a whisk and whisk the ganache until it is well combined and shiny. Scrape down the edges of the bowl with a spatula.
3. Press a piece of plastic wrap over the surface of the ganache, and leave to sit at room temperature for 2-3 hours, or until it has thickened and is a pipeable consistency.

ASSEMBLY

1. Transfer the ganache to a piping bag fitted with a large open star tip such as an ateco #826. Pipe ruffled piping onto the cupcake, by holding the piping tip directly above the cupcake, and piping a mound of ganache. Repeat with the remaining cupcakes. Finish with sprinkles, crispy pearls, or flaky sea salt, as desired.