Cream brown sugar and shortening. Add eggs and beat. Add salt, cinnamon, and baking powder. Dissolve baking soda in boiling water and add to mixture. Add flour and oatmeal. Spoon onto greased cookie sheet and bake 8 to 10 minutes at 350 degrees. Cool completely. Fill, using filling below. Make sandwich cookies. Beat egg whites, add vanilla, 4 tablespoons flour, 2 tablespoons 10X sugar and milk. Add shortening and beat well. Add 4 cups 10X sugar and beat again. Make sandwiches. (I put in plastic sandwich bags or they will stick together.)