Lemon Buttermilk Chess Pie

This recipe came from my friend Brian!! Thanks Brian. This is a VERY rich "Key Lime" custard type pie. Small pieces go a long way.

Pastry for single 9 inch pie
For the filling:
1 1/2 cups brown sugar or (Sugar in the Raw)
1 tablespoon yellow cornmeal (polenta)
1 tablespoon all purpose unbleached flour
1/4 teaspoon sea salt
4 eggs, room temperature
1/3 cup unsalted butter, melted and cooled to room temperature
1 tablespoon finely grated lemon zest
1/3 cup fresh lemon juice
1/2 cup buttermilk, at room temperature
1/2 teaspoon vanilla extract
lemon slices for garnish
1 tablespoon powdered sugar, for garnish
Preheat oven to 350 degrees. Combine the sugar, cornmeal, flour and salt. In a batter bowl, whisk the eggs until light and lemon-colored. Add the dry ingredients to the eggs, blending well. Add the melted butter, lemon zest, lemon juice, buttermilk and vanilla. Pour into the chilled crust and place on middle oven rack. Bake until top is golden brown, 35-40 minutes. When cool, sprinkle with powdered sugar and garnish with lemon slices.