Preheat your oven to 350°F and grease a 9x13-inch baking dish generously. Peel and cube the sweet potatoes into uniform 1-inch pieces for even cooking throughout the dish.
Boil the cubed sweet potatoes in salted water for 12-15 minutes until fork-tender. Drain completely and return to the pot, then mash until smooth with minimal lumps remaining.
Stir butter, brown sugar, orange juice, vanilla extract, cinnamon, nutmeg, and salt into the mashed sweet potatoes. This classic bake base should be smooth and well-combined before adding the eggs.
Beat the eggs separately, then fold them gently into the sweet potato mixture using a spatula. Pour this creamy filling into your prepared baking dish and smooth the top with the back of a spoon.
Bake for 25 minutes until the casserole is heated through and the edges begin to bubble slightly. Meanwhile, toss chopped pecans with maple syrup in a small bowl until evenly coated.
Remove the dish from the oven and sprinkle the pecan mixture evenly across the top. Top with marshmallows in an even layer, then bake for an additional 12-15 minutes until marshmallows are puffy and golden.
Let the thanksgiving sweet potato casserole family recipe rest for 5 minutes before serving. This allows the marshmallows to set slightly and makes serving cleaner and easier.