Preheat the oven to 200 degrees.
Butter a square cake mould and line with greaseproof paper.
Melt the butter.
Mix the flour and the baking powder together.
Process the sesame seeds in a blender.
Whip the eggs and sugar together in a food processor.
Add the butter, sesame paste and the flour-baking powder mixture.
Pour into the cake mould and cook for 30 mins at 180 degrees in a fan oven, check that it is cooked through.
Leave it to cool on a rack before unmoulding.
Boil the cream and pour it over the chocolate.
Leave for 2 mins then mix and add the butter.
Leave to cool and thicken before pouring over the cake.
Spread the icing with a Cristel spatula.
Cut the cake into small squares to serve.