In a medium bowl cream together sugar, butter and vanilla then add egg and combine.
In a medium bowl whisk together flour, salt, baking powder and cocoa, add dry ingredients to creamed mixture with a fork. Move to a lightly floured flat surface and knead gently until you have a soft dough (you may need to add a little more flour, but add a little at a time). Wrap in plastic and refrigerate for approximately 30 minutes.
Pre-heat oven to 350°. Grease and flour an 8 inch pie plate.
Remove dough from the fridge and roll to approximately 1/8 inch thickness (you will have extra dough, perfect for cookies) place in prepared pie plate, prick the bottom a few times with a fork. Cover with parchment paper and add dried beans or pie weights on top, bake for approximately 20 minutes (if pie is not baked, then bake for an additional 5 minutes without the beans). Remove from the oven, remove paper and beans, let cool.