Preheat the oven to 190C/375F/Gas 5.
Grease a six-hole capacity muffin tin with some of the butter.
Place the flour, butter, sugar, eggs and ricotta into a food processor and blend until combined.
Place the banana into a bowl and mash with a fork. Then stir into the muffin dough mixure.
Divide the mixture into six and fill the muffin tin. Transfer into the oven to bake for 12-15 minutes, until the muffins are risen and golden and a skewer comes away clean when poked into the middle of the muffins.
To serve, dust with cocoa powder.