Preheat oven to 350°F.
Melt butter in cake pan in oven.
Remove pan from oven carefully.
Sprinkle brown sugar over melted butter evenly.
Arrange pecan halves over brown sugar layer.
Mix flour, sugar, baking powder, and salt.
Add softened butter, milk, egg, and vanilla.
Beat mixture for two minutes until smooth.
Pour batter over pecans in pan gently.
Bake for 45-50 minutes until golden.
Cool for five minutes in pan.
Run knife around edges to loosen cake.
Place serving plate upside down over pan.
Flip quickly and let pan rest briefly.
Remove pan carefully to reveal topping.