In a large mixing bowl combine ? cup softened butter and 1 cup light brown sugar. Mix in 1 egg and 1 teaspoon vanilla. Stir in 2 cups self-rising flour, until the mixture forms a ball of dough. Divide dough in half. Roll one half thinly on floured waxed paper into an oblong shape and set aside. Mix 2 tablespoons cocoa into remaining dough. Roll out in the same way as the other half of the dough. Flip one oblong on top of the other, and remove waxed paper from the top. Trim edges. Roll like a jelly roll, using the bottom piece of waxed paper to help you move it along, but dont let the waxed paper get caught up the roll of dough. When dough is almost completely rolled, trim the edge at the end into a straight line and pat it into the roll. Also, clean up the left and right end of the roll by cutting off jagged edges. Wrap the rolled dough with plastic wrap or waxed paper. Freeze (for long term storage) or refrigerate (if using soon). When dough is cold, slice it into slices about 3/8-inch wide. Place cookies on greased cookie sheet or baking pan. Bake at 350 for about 12 minutes. (Mine took 11 minutes.) Cool on a wire rack or flat tray. Arrange cookies on a nice serving dish and serve! These cookies taste wonderful?and they look very pretty! I hope you enjoy them!