I believe I first got this recipe several years ago from a Southern Living Book
pastry for a 1 crust pie*
1/2 cup butter, softened
1 1/2 cups firmly packed brown sugar
3 large eggs
1 tbsp flour
1/4 cup buttermilk
2 tsp vanilla extract
powder sugar for dusting, optional
whipped cream for garnish, optional
Preheat oven to 450 degrees.
Fit the pastry into a 10-inch tart pan with a removeable bottom; bake at 450 degrees for 7 minutes. Use pie weights or line with aluminum foil and fill with dry beans to keep flat and in place during baking. Remove from the oven and cool in the pan on a wire rack.
Reduce oven temperature to 350 degrees.
In large mixer bowl, beat the butter and brown sugar at medium speed until fluffy; add the eggs, one at a time, beating well after each one. Stir in the flour and the buttermilk. Add the vanilla, stirring well then pour mixture into the cooled pastry shell.
Bake tart at 350 degrees for 45 minutes or until almost set. Cool completely on wire rack. When completely cooled, remove the pan rim and transfer the tart, still on the pan bottom, to a pretty serving plate. Dust with the powdered sugar, if desired.
Serve each slice with a dollop of whipped cream, if desired.