Blueberry Buttermilk Pie

1 13-inch pie dough
1 1/2 cups granulated sugar
1/4 cup all-purpose flour
8 tbsp unsalted butter melted
3 large eggs
1 cup buttermilk
1/2 tsp vanilla extract
1/2-1 pint blueberries fresh, or frozen
Confectioners sugar for dusting

Pre-heat oven to 325°F. 
Lightly spray a 9-inch pie dish with cooking spray. Place the pie dough into the dish and flute edges, if desired. Set aside. 
In a large bowl, mix together the flour and sugar.
Using a whisk, pour the melted butter into the flour mixture. Mix until totally incorporated.
Slowly add the eggs in one at a time, allowing each addition to be totally incorporated before adding the next.
Add the buttermilk and vanilla.
Whisk until mixed together.
 Drop fresh (or frozen) blueberries, then pour  in the custard. (Will be full, so be careful).
Bake for 60 minutes, or until golden on top and is set in the middle.
Let cool before cutting.
Dust the top of the pie with confectioner's sugar.