Combine everything except pineapple, chocolate and nuts. Put half of the dough in a small bowl. To one half, add the pineapple and mix well. To the other half, add the chocolate and walnuts, and mix well.
Spread chocolate mixture in bottom of greased 13x9 pan. Spread pineapple mixture over the chocolate layer. Use a butter knife to cut through the layers and marbelize.
Bake at 375 for 35-40 minutes. Cool; cut into bars.