Baked Blackberry Dessert from Julie Cantrell

2 cups blackberries mixed with 1/2 cup sugar
1/2 cup butter
3/4 cup sugar
1 3/4 cups flour
1 1/4 tsp baking powder
pinch of salt
1 egg
1 tsp vanilla
1/2 cups milk

Place the blackberries and sugar mixture in the bottom of a buttered baking dish.
Cream the butter until fluffy.
Gradually add the sugar and beat in the egg and vanilla.
Sift together the flour, baking powder and salt.
Add alternately with the milk to the butter mixture.
Mix thoroughly.
Pour batter over the blackberries and bake at 350 for 50 minutes.