Preheat oven to 175C/350F Grease/Spray a 20cm (8 inch) spring form cake tin or pie dish (a 22cm/9inch can also be used).
Mix the dry ingredients in a blender.
Pour the wet ingredients into the dry, and blend until combined. A dough ball will form.
Roll the doughnut between 2 sheets of baking paper and trace a plate/tin bigger than tart tin. Gently place circle in tin. Use excess dough to ensure an even edge.
Alternatively, spread dough evenly in tin and up edges by hand (This is my method of laziest choice!).
Pierce the bottom of pie crust with a knife 4 to 5 times to prevent the dough 'bubbling'.
Bake for 15-20 minutes, or until the bottom is cooked without the edges burning.
Remove from the oven and allow to cool completely before adding the peanut butter mousse.