To Bake Ahead:
Prepare and bake gingerbread as directed. Completely cool in pan on rack. Cover and store at room temperature for up to 3 days. For longer storage, place gingerbread in an airtight container; cover. Freeze for up to 3 months. Prepare the Lemon Sauce as directed. Cool for 15 minutes. Spoon into an airtight container; cover. Store in the refrigerator for up to 3 days. In a small saucepan, heat and stir over low heat just until warm.