Preheat oven to 350 ℉. [No need to pre-heat the oven if you are making the sweet potatoes ahead of time.]
Bring 3 quarts of water to boil in a 6-8 quart pan.
Add sweet potatoes, reduce heat. Simmer until sweet potatoes are tender when pierced with a fork. (About 20 minutes.) Drain and cool.
When cool, peel the sweet potatoes and cut into large chunks. Mash until smooth.
Add brown sugar, 2 tbsp of the butter, orange and lemon zest, orange and lemon juice, and salt. Use an electric mixer to beat until light and fluffy.
Transfer mixture into a buttered 2-2½ quart (or 8x10) baking dish. [NOTE: IF MAKING AHEAD - STOP at this point. Cover and refrigerate up to 2 days.]
Bake sweet potatoes until warm and the peaks are tinged brown. (About 25 minutes.) NOTE: If chilled, allow approximately 15 more minutes.
Drizzle with remaining 1 tbsp melted butter. Serve.
RECIPE TIPS
VEGAN ADAPTATION: Substitute vegan butter or coconut butter for conventional butter.PALEO ADAPTATION: Substitute vegan butter or coconut butter for conventional butter. Omit sugar or substitute maple syrup to taste.PRO TIP: Use the edge of a spoon or the back of a table knife to peel the cooked sweet potatoes.