Make sure the pineapple is well-drained to prevent the batter from becoming too wet. For added flavor, consider toasting the walnuts before adding them to the batter. You can swap the chopped walnuts with pecans or omit them altogether if nut allergies are a concern. Store any leftover cake in an airtight container in the refrigerator to keep it fresh for about 4-5 days or freeze for up to three months.