Savory Galette Crust

1 stick cold unsalted butter
1 1/3 cups flour
1/4 teaspoon salt
1 pinch sugar
1/4 cup grated Parmesan
1/3 cup ice water (only add as much as needed)

Make the dough:
(Can be made ahead and refrigerated for a day or two.)

Grate the butter into a small bowl and place in the freezer for about 8 to 10 minutes. In a large bowl, mix flour, salt, sugar, and cheese. When the butter is nice and cold, incorporate it into the flour mixture using a pastry cutter, your fingers, or a food processor. When the mixture begins to clump together, slowly add water, only adding as much as needed to form a ball – start with 1/4 cup and increase as you mix. You don’t want a wet dough. On a floured surface, shape ball into a disc and wrap tightly with plastic wrap. Refrigerate for an hour before using.

Assemble the galette:
Heat oven to 400°F.
 
Lay out a large sheet of parchment paper on your work surface. Remove dough from refrigerator and, with a lightly floured rolling pin, roll out dough into a somewhat round shape, about 1/8 inch thick. Fill with potatoes, vegetables, herbs, etc. Fold the edges of the dough over, brush with egg wash, and bake for about 45 to 50 minutes, until golden brown. Let cool for about 5 to 10 minutes before serving.

From Epicurious