Place the flour, cocoa, sugar, and salt into the bowl of a food processor. Pulse to mix. Cut the frozen coconut oil into pieces and add them to the bowl of the food processor. Pulse them into the flour mixture 10 times or cut the frozen oil pieces into the dry ingredients by hand, using two knives or a pastry cutter.

Add the egg and 1 tablespoon of the ice water to the bowl of the food processor. Pulse the mixture five times or mix it gently by hand. Add another tablespoon of the ice water and pulse the mixture another five times or mix it again gently by hand. Add the last tablespoon of water, pulsing or lightly mixing the dough for 10 to 15 seconds, until it looks like clumps of couscous; the dough does not have to come completely together.

Cut off a large piece of plastic wrap, place the dough on top of it, lift the sides of the plastic to wrap it around the dough, and then flatten it into an eight inch (20 centimeter) pancake. Place the dough in the freezer for 15 to 20 minutes, until it feels firm, but you can still press into it a little.

Preheat the oven to 425 degrees and place a rack in the lowest position in your oven. Cut off a large piece of Gefen Parchment Paper and sprinkle it with some all-purpose flour. Remove the dough from the plastic wrap and place it on top of the parchment. Sprinkle some flour on the dough and then place a second piece of parchment on top. Using a rolling pin, roll over the top of the parchment to smooth out the dough into a 12- to 13-inch (30- to 33-centimeter) round shape. Peel back the top piece of parchment paper and sprinkle some more flour over the dough, once or twice, while you are rolling. Place the parchment and rolled crust onto the cookie sheet or jelly roll pan.

Prepare the filling: Place the fruit in a medium bowl. In a small bowl, mix together the sugar and cornstarch, then sprinkle it on top of the fruit and mix it in gently until the flour dissolves.

Beat the reserved egg white with a fork, then brush the egg white all over the dough. Sprinkle it with the remaining teaspoon of sugar if you like. Bake for 30 minutes, then remove the pan from the oven. Using oven mitts, move the rack to the middle position, then move the galette back to the rack and bake for another five to ten minutes or until filling looks bubbly. Let cool for 20 minutes and serve, dusted with confectioner’s sugar if desired.

Place the fruit in the center of the dough circle and spread it outward, leaving a two to three inch border. Fold about two inches of the border over the fruit, leaving the fruit-filled center open. Fold over another two inch section of the border and repeat this step, pressing one section of the border into the next, so that you end up with dough pleats all the way around. This will seal in the fruit (and fruit juices). Use a pastry brush to dust off any excess flour on the dough.