Peel and chop the sweet potatoes into ½-inch chunks, aiming for even sizes so they cook uniformly. In a medium pot, combine the sweet potatoes, brown sugar, maple syrup, butter, orange juice, vanilla, salt, and spices. Stir well to coat the potatoes completely.

Warm over medium heat, stirring as the butter melts, until the sauce reaches a gentle boil. Reduce the heat to low, cover, and simmer until the sweet potatoes are fork-tender, about 40–45 minutes. Start checking after 20–25 minutes; small pieces may finish sooner. Stir gently from the bottom occasionally, and move to the next step as soon as a fork slides in easily.

Uncover and simmer for about 5–10 minutes, just until the sauce coats the pieces. Stir gently and watch closely so the sugar does not scorch. If the sweet potatoes are already soft, lift them out with a slotted spoon and reduce the sauce by itself, then spoon it over them. The syrup thickens a little more as it cools.

Preheat the oven to 375°F (190°C). Toss the sweet potatoes with brown sugar, maple syrup, melted butter, orange juice, vanilla, salt, and spices. Transfer to a greased 9×13-inch baking dish. Cover tightly with foil and bake for about 45–50 minutes, turning gently halfway through. Begin checking tenderness at 30 minutes; uncover sooner if the pieces are already nearly tender.

Remove the foil and bake for about 15–20 minutes more, only until the sweet potatoes are fork-tender and the sauce coats them. Plan on roughly 60–70 minutes of baking altogether, but let tenderness guide you. If the potatoes finish before the syrup thickens, remove them and reduce the sauce separately rather than overcooking them. Let cool slightly before serving.

Place the sweet potatoes in a 4- to 6-quart slow cooker. Add brown sugar, maple syrup, melted butter, orange juice, vanilla, salt, and spices, then toss to coat. Cover and cook on low for about 6–7 hours or high for about 3–4 hours. Check before the end of the range, especially in a larger cooker, and stop when the pieces are fork-tender. Keep the lid on between checks and turn the pieces gently if needed; slow cookers vary.

For a thicker sauce, lift the tender sweet potatoes into a serving dish with a slotted spoon. Carefully pour the cooking liquid into a saucepan and simmer uncovered until it coats a spoon, stirring frequently. Spoon the sauce over the sweet potatoes and serve warm. This thickens the sauce without cooking the potatoes until they fall apart.