1. Preheat oven to 325°. Fit piecrust into a 10-inch cast-iron skillet; sprinkle piecrust with powdered sugar.
2. Whisk eggs in a large bowl until foamy; whisk in brown sugar and next 6 ingredients. Pour mixture into piecrust, and top with pecan halves.
3. Bake at 325° for 30 minutes; reduce oven temperature to 300°, and bake 30 more minutes. Turn oven off, and let pie stand in oven, with door closed, 3 hours.
*Vanilla extract may be substituted.