Mix dry ingredients of the crust in a medium bowl.
Either grate or cut up chilled butter in small pieces and add the butter to the dry ingredients. Using your hands, gently rub butter into the flour mixture to create a uniform grains which resemble coarse meal. If the butter is not chilled, this process is nearly impossible to achieve. Please use chilled butter.
Add grated orange zest to the buttery flour mixture and mix it in. Add cold milk and give everything a mix with a fork.
Using your hands pull together all the crumbs in one place and round the dough up. Please do not kneed the dough. All you need is to stick everything together to make a ball. Give the dough a patty shape and cover it with a plastic wrap. Refrigerate the dough for about an hour.
When the dough is rested and chilled in the refrigerator take it out and roll it out (about 10 inches) on a parchment paper or on a working surface. Use a little bit of flour if the dough is a little sticky. They dough may not come out very round and uniform. Some cracks are expected, just glue the edges together and keeping rolling until desired size is reached. You can keep the parchment paper under the dough for baking, too. Place the dough on a cookie sheet or a baking pan big enough to accommodate8 inch round galette.
Position the rack in the center of the oven and preheat the oven to 380 degrees F.
In a medium bowl mix together sugar, lemon juice, corn starch, and cinnamon. Add pitted cherries to the mixture and gently toss everything together, covering all the cherries.
I also rubbed a little bit of corn starch on the dough. But I found this step to be unnecessary. Trial and error, my friends. Place the cherry mixture in the middle of the dough, leaving 2-inch border from the sides. Gently fold the dough from the sides to the center, leaving the middle fruit part exposed. Pleat loosely and pinch the dough to seal any cracks. Brush the sides of the galette with the wash and sprinkle some brown sugar on them.
This step is also optional, but I did it in order to aid cherries to keep some of their shape in tact. Cut out a small circle fitting just the center of the galette and use as a cover before putting the galette in the oven.
Bake the galette for about 40 minutes or until the crust is nicely golden brown.