Preheat oven to 350°F. Coat 9-inch round cake pan with non-stick cooking spray. Melt 2 tablespoons butter and combine with brown sugar in a small bowl.
Crumble the mixture over the bottom of the prepared pan and pat it into an even layer. Evenly top with berries; set aside.
Combine flour with baking powder in a medium bowl; set aside. Beat sugar with remaining butter in a large bowl with an electric mixer until creamy. Beat in egg, vanilla extract, and lemon peel. Alternately beat in flour mixture and milk until blended. Pour over berries.
Bake 40 to 45 minutes until a toothpick inserted in the center comes out clean. Cool 5 minutes on a wire rack; invert onto a serving plate. Serve warm or at room temperature and dust with confectioners’ sugar if desired.