Raspberry Peach Cobbler

6 medium peaches (about 1 3/4 lbs)
3 Tbsp powdered sugar
1 cup raspberries
3/4 cup flour
3 1/2 Tbsp sugar, divided
1/2 tsp baking powder
1/4 tsp baking soda
1/4 tsp salt
3 Tbsp butter
1/3 cup sour cream
1 tsp vanilla

In a bowl, toss peaches with powdered sugar until sugar dissolves.  In a 8 inch square baking pan, arrange peaches and raspberries.  In a large bowl, combine flour, 3 Tbsp sugar, baking powder, baking soda and salt.  Cut in butter.  Add sour cream and vanilla.  Mi with a fork until dough comes together. 

Crumble mixture over fruit and sprinkle with 1/2 Tbsp sugar.  Bake until golden brown and fruit begins to bubble, about 40-45 minutes.  Cool 10 minutes before serving.