Method
Line a 20 cm (8 inch) square tin with parchment, leaving overhang on two sides.
Stir the almond butter, maple syrup and vanilla in a bowl until smooth. Warm for 15 seconds in the microwave if stiff.
Add the protein powder, coconut flour and salt and stir, then knead with your hands until it forms a smooth dough. Add 1 tsp of water if crumbly.
Fold in the chopped walnuts and press the mixture firmly and evenly into the tin.
Chill for at least 1 hour, then lift out and cut into 16 squares. Keep in the fridge for 1 week or freeze for 3 months.
Storing and reheating
Keeps 2 weeks in the fridge.