Sift flour and salt into a large bowl. Add cubed butter and with a pastry cutter cut in chilled butter until most of the butter is cut in - not so that it's fully crumbled and all uniform, just so that it's mostly incorporated.
Make a well in the flour butter mixture and add chilled water. Slowly mix in to a dough. It will be shaggy at first and it will feel very dry but keep kneading it and it will form. Form it into a ball and then wrap dough in plastic wrap and then chill in fridge for at least 30 minutes.
Prep Cherry Filling
Mix pitted cherries with all other filling ingredients and mix well. You can make this up to 24 hrs in advance and store in fridge.
Assemble Galette
Pre-heat oven to 375 degrees.
Line a baking sheet with parchment paper. Remove parchment paper from the cookie sheet and add it to the counter. Roll out dough on parchment paper into a 1/4 to 1/8 inch thick 7-8 inch round circle. Sprinkle the center of the dough with semonlina flour.
Add cherry filling to the center of the dough and then fold up the edges of the dough so they just start to cover the filling. The more "rustic" the better - don't worry about if it's uneven.
Whisk egg in a small bowl and brush folded over edges of the galette with egg wash. Sprinkle with sugar.
Bake for 40-45 minutes until edges of the galette are browned.
Serve immediately and top with ice cream!
Notes
Use either butter or unsalted butter - if you use unsalted butter just add another 1/4 teaspoon of salt. Once baked, this yields about an 8 inch diameter galette.