This was a Bake Off with friends from around the world. There was some confusion on conversions and ingredients, but I crossed my fingers, tried hard and hoped for the best. The photo above is actually my cake. I made the recipe below but excluded the coffee. I also made one error, but it tasted good enough. At the bottom, I'll share my little flub.
8.81oz (or ½ pound) butter, cut into cubes
8.81oz (or ½ pound) dark chocolate, broken into pieces
1 tbsp instant coffee powder (or granules)
2 tsp vanilla extract
¼ cup extra-light olive oil (or vegetable oil)
½ cup buttermilk
1 cup self-raising flour
1 cup plain flour
½ cup cocoa
½ tsp bicarbonate of soda
2 cups caster sugar
2 cups thickened cream
17.1oz (or 1 pound) dark chocolate (extra), roughly chopped
1 Preheat oven to 320F. Grease and line a 8.7inches round cake pan with baking paper. Put butter, chocolate, coffee, vanilla and ¾ cup hot water in a saucepan and stir over low heat until chocolate is melted and smooth. Remove from heat.
2 Combine eggs, oil and buttermilk in a large jug. Sift flours, cocoa and bicarbonate of soda into a large bowl. Add sugar and stir until well combined. Make a well in centre of flour mixture and add egg mixture. Stir slowly to combine. Add chocolate mixture, stirring constantly until well combined.
3 Pour mixture into prepared cake pan and bake for 1 hour 45 minutes or until a skewer inserted in the centre comes out clean. Cool cake in pan.
4 To make ganache, put cream and chocolate (extra) in a heavy-based saucepan over medium-low heat. Stir until chocolate has melted and mixture is smooth and well combined. Pour into a bowl. Cool at room temperature or refrigerate until ganache is spreadable. Decorate cake with ganache.
Measurement conversions for grams to pounds were obtained by using the calculators here.
For converting cooking measurements, this website seems good. It lists UK, US and Aust measurement for everything and indicates that the cup measurements and even the teaspoon (tsp) and tablespoon (tbsp) measurements are also slightly different in each country, but I haven't converted tsp/tbsp in the above recipe. You can read more here.
SIDENOTE: I had a bowl with my dry ingredients, wet ingredients and chocolate sauce to make the cake. I put the oil in with the chocolate sauce instead of with the wet ingredients. I don't feel it affected things too much. I'd be willing to make the cake again. I will warn that it is a very heavy cake. I didn't cook mine the entire time. I cooked mine is an 8x8 baking pan and took it out around an hour in when it was done. It puffed a lot, but it tasted done to me. However, I know some who did cook the entire time. Someone said they cut the cake in half and did a layer of ganache in the middle, and I don't see how that's bad at all.