Peach Galette

INGREDIENTS

• Scant 1/2 teaspoon kosher salt
• 1 1/2 teaspoons milk
• 1 tablespoon granulated sugar
• Turbinado sugar, for sprinkling
• 1/2 teaspoon ground cinnamon
• 1 tablespoon beaten egg or heavy cream
• 3/4 cup unbleached all-purpose flour, plus more for working with the dough
• 6 to 8 soft peaches or with give, peeled, halved, pitted, and cut into 1/4 to 1/2-inch-thick wedges
• 3 tablespoons unbleached all-purpose flour or tapioca flour
• 1 large egg
• 1/2 cup granulated sugar
• 1/2 cup plus 1 tablespoon cold unsalted butter, cut into small chunks
• 6 tablespoons whole wheat flour