In a large bowl, combine the flour, 1/2 cup brown sugar and baking powder. Cut in butter until crumbly. Gradually add milk, dates and walnuts.
In a large saucepan, combine water and remaining brown sugar; bring to a boil. Remove from the heat; add the date mixture and mix well.
Transfer to a greased 10-in. cast-iron skillet or 8-in. square baking pan. Bake at 350° for 25-30 minutes or until top is golden brown and fruit is tender. Serve warm, with whipped cream and cinnamon if desired.