Preheat the oven to 170C and line a large baking tray with greaseproof paper.
Place the oats, cacao/cocoa powder and Natvia in a bowl.
Whisk the nut butter, oil, egg and vanilla then pour into the dry ingredients and mix well to form a dough.
Divide into about 8 pieces, roll into balls then place on the baking tray and flatten with the palm of your hand. Stick your thumb in the middle of each to make an indent and push a blueberry in the middle.
Bake for 10-12 minutes then leave to cool - and enjoy!