Serve warm with whipped cream or let cool into hard gingerbread. .
Cream butter until the consistency of mayonnaise. Beat in brown sugar and continue beating until fluffy. Stir in egg and molasses. Sift together flour, spices, salt, and baking powder, add to creamed mixture, and stir in gradually. Chill thoroughly. Preheat oven to 350 degrees F. Roll dough ¼-inch thick on lightly floured board and place on greased cookie sheet. Combine white sugar and instant coffee and sprinkle over top. Bake for 20 minutes. Remove from oven and cut into squares.