In a medium saucepan, heat milk and pumpkin pie spice, until boils gently. Add oat flakes, let it cook again, reduce heat, and keep cooking 5 minutes. Add the pumpkin, vanilla and brown sugar. Cook for 1 minute until everything is hot, but which does not boil. Divide into two portions into two bowls, pour milk over, and sprinkle with walnuts and crystallized ginger. Makes 2 servings, 7 ounces of milk per serving.