Preheat oven to 180 degrees Celsius
Cut the butter into small cubes. Add to a food processor or blender with the almond butter and dry ingredients. Pulse until the mixture comes together.
Line a slice tin with baking paper. Press ? of the mix into the tin firmly. Bake in the oven for 10 minutes, then set aside.
While the slice is in the oven, heat together the blueberries, chia seeds, flour and sugar in a small pot, stirring regularly until the berries are defrosted.
Spoon the berries on top of the base and crumble the remaining base mixture over the top.
Bake for 20-25 minutes, until just golden.
Leave to cool completely in the tin, then cut into slices. Dust with icing sugar and sprinkle with chopped almonds.
Keep the bars in an airtight container in the fridge.