Black treacle is an important part of Christmas cakes. If you do not have black treacle, you can use another type of molasses or even dark brown sugar. Both of these will give your cake a deep, rich flavor that is perfect for the holidays. You can also apply honey or maple syrup to substitute for the black treacle. These will add a bit of sweetness to your cake without making it too heavy. Whatever you choose, ensure to adjust the other ingredients accordingly so that your cake turns out perfectly.