Start by mixing together your instant coffee with your cool water. Stir until dissolved and then place in the refrigerator to chill thoroughly while you prep your dough.
1 tablespoon instant coffee, ½ cup water
Next mix together your dry ingredients - the flour, cocoa powder, brown sugar and salt. Cut in your cold butter. Using your hands rub this into the dry ingredients until you have a coarse sandy texture - your goal isn't to break down all of your butter - bits of butter contribute to the flakey texture.
1¼ cup all-purpose flour, 2 tablespoon cocoa powder, 2 tablespoon light brown sugar, pinch salt, ½ cup unsalted butter
Slowly add your cool coffee into the dough mixture, starting with ¼ cup. Gently mix with your hands until it comes together into a dough. Avoid overadding water and overworking the dough as this can make for a stiffer, less flakey crust. You may find that you do not need all of the coffee or need to add a little more cold water depending on various conditions (like humidity or temperature in your kitchen).
Once you've brought your dough together into a ball, wrap this with plastic wrap and gently flatten into a disc. Place this in the refrigerator to chill for at least 2 hours.
After 2 hours, pre-heat your oven to 350℉ (175C/155C Fan). Unwrap your dough and place on a work surface, lightly dusted with cocoa powder. The cocoa powder will act like flour for rolling out the chocolate crust. Roll out to a circle approximately ¼" thick. Use this to line your pie plate and then use a fork to prick your dough all over the bottom and sides.
Use a scrunched up piece of parchment paper to line the inside of the crust and fill with baking beans or rice to blind bake. Place in the center of your preheated oven to bake for about 30 minutes. Then remove your weighted parchment filling and bake for a further 5-10 minutes until the crust appears dry.
Remove from the oven and set aside while you prepare the filling.