Cranberry Blueberry Cobbler

I found this similar version of this recipe on Martha Stewart's website (just with cranberries but not enough).  But because I cannot follow I recipe I changed it and like it better this way.

Cranberry Blueberry Cobbler

1/2 cup milk
1 egg
1/2 cup melted butter
1 cup flour
1 1/4 teaspoon baking powder
1/2 cup sugar
2 cups cranberries
1/2  to 1 cup blueberries

Preheat oven to 350.  Butter an 8 inch cast iron pan.

Whisk together milk and egg, add melted butter.  Whisk in flour, baking powder and sugar.  Mix in berries. Pour into buttered pan and bake for around 40 minutes until done in the center.