• Prepare cheddar pie dough.
• Shred cheese using large grater holes. Keep chilled until ready to assembly.
• Place sliced tomatoes on paper towel lined plate to absorb any excess moisture for about 10 minutes.
• Egg Wash: Whisk together egg, water, and salt until smooth and well combined. Set aside.

Assembly:

• Roll the dough on a lightly floured work surface. Roll dough to about 14 inches in diameter and about ¼-inch thick
If the dough is too hard or too cold, let it rest a few minutes until it is pliable.If dough is too soft, let it chill in the fridge for a new minutes to harden.
• Sprinkle about 2/3 of shredded cheese in center of dough, leaving about a 2-inch exposed border. Arrange tomato slices in an even layer over cheese.
• Brush egg was along the exposed perimeter around the cheese-tomato filling. Season tomatoes with salt and pepper. Sprinkle remaining cheese over. Fold the edges of the dough up and over about 1 inch into the filling. Press the folds together to seal.
• Refrigerate assembled galette for at least 30 minutes, until dough is cold and firm.

Bake

• Preheat oven to 400℉.
• Once oven is the correct temperature, remove galette from the fridge. Brush crust with egg wash. Place galette in lower ⅔ rack of oven. Bake for 20 minutes.
• Reduce temperature to 350℉. Rotate baking sheet and bake for another 20-30 minutes until crust is golden brown and filling mixture is bubbling and boiling.
• Leave on sheet tray for 5 minutes. Transfer galette to wire rack to continue cooling (allow air flow under crust). Cool for at least 15 minutes before slicing and serving. Serve warm or at room temperature.