Preheat oven to 350°F (180°C).
Grease a 9-inch (23 cm) cake pan with butter.
In a medium bowl, mix the butter, sugar, and brown sugar until fluffy.
Add the eggs one at a time, then add the vanilla. Whisk until combined.
Fold in the flour, salt, cinnamon, and baking powder until combined.
Fold in the berries.
Transfer to a baking pan.
Bake for 40 minutes, or until golden brown.
Cool for 30 minutes before serving.
Slice and sprinkle with powdered sugar.
