Butter and flour a 9-inch cake pan with removable rim. Add 1 cup flour and baking powder. Stir to combine, then beat on high speed until the stiff batter is well blended, about 2 minutes.
Scrape batter into cake pan and spread top smooth.
Drain wine marinade from berries and save. Evenly spoon berries and 2 tablespoons of the marinade over batter. Run a thin-bladed knife between cake and pan rim. Let cool at least 10 minutes. Remove pan rim and sprinkle cake with a little more sugar.