Pour the maple syrup mixture over the sweet potatoes; toss to coat and spread the potatoes out evenly. Place sweet potatoes and onions into a 9-by-13-inch glass baking dish. They can also be frozen up to a month or more (adding a tablespoon of lemon juice will help prevent browning). DIRECTIONS. This recipe for Mashed Sweet Potatoes can be completely prepared up to 2 days ahead. Who doesn’t like potato skins? Men and women, and kids of all ages will enjoy these Sweet Potato Skin appetizers from my KITCHEN 101 cookbook. Watching football, tailgating or watching the Super bowl, this #1 bar food is everyone’s favorite. Cook whole unpeeled potatoes in boiling water until fork-tender but not mushy; Place in cold water to stop cooking; carefully cut each cooked potato in half; With a melon baller or small spoon, scoop out centers, leaving a 1/4-inch shell of pulp in skins(Use centers for soups or salads). These healthy sweet potato skins make the most amazing, make-ahead healthy sweet potato appetizer. Make Ahead Tips: Mashed sweet potatoes can be made up to 3 to 4 days in advance. Reheat in the oven, covered, at 350F for 15 to 20 minutes. Cover with foil and bake the for 15 minutes. Keep them tightly covered in the refrigerator. When completely cooled, place the mashed potatoes in an airtight container, cover, and refrigerate. MAKE AHEAD MASHED SWEET POTATOES.