Preheat the oven to 180C. Grease and line a 23cm square tin. In a medium saucepan heat the butter until just melted. Break the chocolate into pieces and add to the pan. Stir over a very low heat until fully melted and combined. Remove from the heat. Stir in the sugar and Protein 22. Beat well.
Next add the oat flour and the eggs. Again beat well until mixed through properly.
Pour the mixture into the prepared tin then scater the top with the nuts.
Bake for 25 minutes until slightly risen, but still a little soft in the middle.
Allow to cool fully before placing in the fridge for at least 2 hours. This helps the brownies develop a fudge like texture. Slice into squares or whatever shape you fancy and serve with another dollop of Protein 22, or simply on its own.
Store at room temperature in an air tight container for up to 4 days.