Bring to a boil and cook until it forms a soft ball (3 to 4 minutes, or 232 degrees). Remove from heat and add 2 cups peanut butter and 2 cups marshmallow creme. Beat until smooth. Pour 1/2 mixture into a greased 9 x 13 inch pan. Add 1/2 cup cocoa to remaining dough. Add to light portion and swirl. Recipe may be cut in half and an 8 x 8 inch pan used.