In a bowl beat together the butter, brown sugar, vanilla, and egg. Mix the flour, baking powder, and salt in the top of a sifter, set over the butter-mixture bowl, then sift into the bowl alternately with the sour cream. Blend well, then fold in the rhubarb. Spread the batter into a greased 8-inch square pan. Crush the sugar lumps and mix with the mace. Sprinkle over the top of the batter and bake in a preheated 350 F oven for 45 minutes. Makes one 8-inch square cake.
[ The L. L. Bean Book of New New England Cookery ]
