1. Using electric mixer, cream the butter. Add the sugar and mix well. Add the eggs and vanilla. Slowly add the flour, baking powder and salt. Knead the dough well.
2. Form the dough into 4 balls and place in the refrigerator overnight.
3. Preheat the oven to 350 degrees.
4. Roll each ball of dough into a flat rectangle about 10x6 inches and 1/8 inch thick. spread the marmalade or sprinkle with the cocoa mixture. Roll jelly-roll fashion, starting at one of the long ends.
5. Place two of the rolls on each of 2 large greased cookie sheets, leaving room between them because they will spread and flatten out. Bake about 20-30 minutes, until golden brown. When cool, slice at an angle at 1 1/2-inch intervals, making finger-length slices.