With a pastry blender of fork, cut margarine into the flour in a mixing bowl until the mixture resembles cornmeal. Do this rapidly so the butter does not melt. Add the sugar and if desired, 1/2 cup of raisins. In a small bowl, beat the egg and milk together until mixed. Reserve 1 TBSP of this mixture to brush the tops of the lembas. Add the cream and egg mixture to the flour and mix just until combined into a stiff, soft dough. Knead three or four times on a lightly floured surface. Roll dough to a 3/4" thickness and cut with an oval or leaf shaped cookie cutter. Place on a lightly greased baking sheet, leaving 1" of space between lembas. Brush the tops of the lembas with the reserved egg-milk mixture. Bake for 12 -13 minutes in a preheated 400 degree oven.
For safe keeping, wrap each lemba individually in a fresh, clean mallorn leaf. If these leaves are unavailable in your area, store the lembas in a tightly closed container. Makes about 1 1/2 dozen lembas.