To prepare Uncle Jim's Scotch Shortbread Bake goods recipe, first you need to prepare the ingredients for the shortbread. In a large bowl, mix together the flour, baking powder, sugar, and salt. Then add the butter and mix until the mixture is light and fluffy. Add the vanilla and stir until combined. Pour the batter into the greased and floured pan and bake for 20 to 25 minutes. Remove from the oven and allow to cool before cutting into squares.