Butter 5 or 6 custard cups. In a small saucepan, melt 2 tbsp butter; add brown sugar. Stir until sugar is melted & begins to bubble. Divide sugar mixture between custard cups. Place a pecan half (upside down) in center of each cup. Place sliced persimmon quarters in a circular fashion on top of sugar & pecan. Set aside.
Preheat oven to 350 F. In a bowl, beat remaining 4 Tbsp butter & granulated sugar until fluffy. Whisk in vanilla, egg & milk until fully blended.
In another bowl, whisk together flour, baking powder & salt. Add to wet ingredients, mixing ONLY until blended. Carefully fold in chopped pecans.
Divide batter between custard cups & bake for 20 minutes. Test with a toothpick. Allow to cool for 5 minutes in custard cups. Invert on serving platter & serve.