Execution for the cake
Preheat the oven at 180°C.
Cut some parchment paper, and line it in a 24 – 26 cm tin.
Put the butter in a non-stick frying pan at a high heat, stirring for 5 minutes until it melts.
Transfer the melted butter to a large bowl and add the flour, cocoa, baking soda, icing sugar, brown sugar, maple syrup, eggs, banana, and milk, and stir until smooth.
Put the mixture in the tin and bake for 1 hour and 10 minutes or until cooked.
Leave it to cool in the pan and, after unmoulding it, place it on a grill to cool it well.
Execution for ganache
Put the dairy cream and the chocolate in a ben Marie (double boiler) and mix until the chocolate melts and is homogenized with the cream.
Set aside to cool a bit so it has a thicker form.
Pour the ganache over the cold cake.