Preheat oven to 350 degrees F (175 degrees C). Grease a 9x13-inch baking pan.
In a large saucepan over medium heat, combine brown sugar and water. Add raisins, nuts, candied citron, shortening, salt, nutmeg, and cinnamon; bring to a boil and boil 3 minutes. Remove from heat and cool.
Sift in flour and baking powder; stir until well blended. Pour into prepared pan.
Bake at 350 degrees F (175 degrees C) for 45 minutes or until a toothpick inserted in center comes out clean. Remove from oven and cool on a wire rack. Leave in pan and cut into squares. .