Preheat oven to 180˚ C (350˚F). Prepare base by combining flour and brown sugar; cut in butter. Press into a greased 2L (9” x 9”) cake pan and bake 15 minutes or until slightly browned.
Meanwhile, prepare topping by combining oats, salt and baking powder; set aside. Beat eggs until light and thick, then beat in brown sugar; stir in mincemeat. Add dry ingredients and mix until well combined. Pour topping over partially baked base and bake an additional 25 – 30 minutes. Cool, then cut into squares.