Line a 9x9 inch baking pan with parchment paper. Set aside.
In large bowl, mix flours, protein, sweetener and salt and mix well.
Combine cashew butter and syrup in microwave bowl and heat until melted about 30 seconds. Stir together until smooth.
Pour mixture into dry and mix until well-combined, about 3 minutes. Add vanilla and milk and mix well until a firm batter is formed. If necessary, add more milk by the tablespoon until the right density is reached.
Transfer dough to lined baking dish and press down firmly to create an even layer.
For the glaze, mix all ingredients in a small bowl and slowly add the milk until desired consistency is reached. Pour over bars.
Refrigerate for at least 30 minutes to firm. Cut into square or rectangle pieces and store in the fridge for up to one week.