In a medium bowl, whisk together 1 1/2 cups cornmeal, 3/4 cup all-purpose flour, 1 tablespoon baking powder and 1/2 teaspoon salt. Using your fingers, rub 1/4 cup butter (cut into cubes) into flour mixture until it resembles coarse crumbs. (Or use a handheld pastry blender.) Add 3/4 cup buttermilk and one egg. Stir with a fork until dough comes together, adding drizzles of buttermilk, if necessary, to moisten. On a baking sheet lined with parchment paper, press dough to 1/2-inch-thickness. (Don't worry about the shape.) Bake in a 400° oven for 12 to 15 minutes or until golden brown and crisp on the edges. When cool enough to handle, coarsely crumble. Use immediately or chill in an airtight container for up to 3 days.
Our corn bread is thin and dry so that it can be baked and crumbled right away for dressing. You can substitute 7 cups of any crumbled dried corn bread.
At this point, cover and refrigerate up to 12 hours. Remove from refrigerator 45 minutes before baking. Increase oven temperature to 425° when you remove the turkey from the oven. Bake dressing while turkey rests.