In a saucepan heat stout, coffee and butter together until the mixture comes to a gentle simmer, add cocoa powder while whisking continuously to avoid lumps until smooth. Set aside to cool.
Blend flour, sugar, baking soda, and salt in a different bowl. Mix eggs, vanilla and creme fraiche with an electric mixer in bowl no 3.
Now check on your chocolate mixture and make sure it’s cool enough to continue the process.
Add the chocolate mixture to the egg and creme fraiche mixture and blend them together.
Add flour mixture a little bit a time and beat on low speed until combined. Pour into the pan and level.
Bake in the preheated oven for 25-30 min. Always test your cakes for doneness with a toothpick or a cake taster. Cool on a wire rack.