Preheat the oven to 180°c. Line a muffin pan with patty pans.
Blend the beetroots in a food processor or blender to a rough purée.
Melt the chocolate in a bowl suspended over a pan of hot water. Pour in the hot coffee. Chop the butter into cubes (approx. 1cm cubes) and stir into the chocolate. Remove the bowl from the water and stir, allowing the butter to melt.
Sift the flour, baking powder and cocoa together in another bowl and set aside.
Separate the eggs. Whisk the yolks in another bowl until frothy. Add the sugar and whisk until pale yellow.
Add the chocolate mixture to the eggs and mix briefly then fold in the beetroot purée.
Whisk the egg whites in a separate bowl until soft peaks form.
Fold the egg whites into the chocolate mixture, then fold in the flour mixture.
Fill the patty pans until they are 2/3 full and bake for 18 minutes or until a skewer inserted into the cake comes out clean.
Allow the cupcakes to cool totally before frosting.
For the frosting
Melt the chocolate using whatever method you prefer.
Add the creme frâiche and vanilla essence and whisk until well combined.
Allow to cool to room temperature, stirring occasionally. The frosting will be runny at first but it will thicken nicely as it cools. Whisk the frosting occasionally to avoid lumps.
Once the frosting has cooled and thickened, use it to frost the cupcakes.
Don't use a can of (pickled) beetroot! You will taste the vinegar from the 'juice' in the beetroot, and it will not be good in the cupcakes. Plain beetroot has a subtle sweetness, which lends itself to the cupcakes. You can normally find cooked and peeled beetroot vacuum-sealed in the fruit and veg department of your supermarket.If you can't get creme frâiche for the frosting, or it is expensive, use sour cream.