1 1/4 cups unbleached all-purpose flour (plus extra for rolling out the dough)
1/2 cup whole wheat pastry flour
1/2 cup old-fashioned rolled oats
1 tablespoon Sugar
1/4 teaspoon salt
12 tablespoons unsalted butter (1-1/2 sticks, cold, cut into 1/2-inch pieces)
2 tablespoons ice water (or more as needed)