1. Soak corn husks in warm water to cover 1 hour or until softened. Drain and pat dry.
2. Press 2 Tbsp. dressing into a 3- x 5-inch rectangle along 1 long side of 1 husk, leaving borders along other 3 sides of husks. Spoon 1 Tbsp. leftover sweet potato casserole down center of dressing. Roll up dressing, starting with long side and using husk as a guide. Press dressing edges together to form a seal, enclosing filling. Fold long side of husk over tamale to enclose.
3. Fold ends toward center to seal. Repeat procedure using remaining husks, dressing, and sweet potato casserole.
4. Place 6 tamales side by side on work surface, with seam sides inward; tie tamales together with kitchen string, securing bundles at both ends. Repeat procedure to make a total of 4 bundles.
5. Stand tamale bundles on end in a steamer basket; place basket over boiling water in a large Dutch oven. Cover and steam 35 minutes or until dressing is set, adding more boiling water as needed. Serve hot with Spicy Cranberry Salsa.