In a large bowl, stir together the nut butter and maple syrup.
Add the puffed rice, and gently stir to combine.
Pour the mix out onto baking paper, gently pressing to a large square shape, around 1cm in thickness.
Place the sheet on a tray or plate and refrigerate for one hour until set.
Remove from the fridge and cut into squares.
Enjoy.
Store in an airtight container for up to one week.