Arrange sweet potatoes, shallots, thyme, and sage in a 9×13-inch baking dish. Avoid overlapping the sweet potatoes too much. Sprinkle with a pinch salt and pour olive oil over top until mostly submerged. It’s okay if some sweet potatoes are exposed, but they should be mostly covered.
Bake the sweet potatoes:
Transfer the baking dish to the oven. Bake uncovered for 1 hour 15 minutes or until the potatoes are very soft. Remove from the oven.
Using a slotted spoon, remove the sweet potatoes and shallots from the dish and transfer them to a paper towel-lined plate. Pick the sage leaves from the oil and add them to the plate with the sweet potatoes. Discard any remaining herbs in the oil. See note.
Prepare the pomegranate maple butter sauce:
Combine pomegranate juice and maple syrup in a small saucepan. Bring to a boil. Reduce heat and simmer for 10 minutes.
Spoon 2 tablespoons of the sauce into a small bowl. Add the cornstarch and whisk until a slurry forms. Set aside.
Mount the cold butter into the saucepan. Whisk until glossy and combined. Simmer for 2–3 minutes. Slowly whisk in the cornstarch mixture and continue simmering until thick, 2–3 minutes more. Turn off the heat.
To serve:
Transfer the sweet potatoes to a serving platter. Arrange the cooked sage leaves and cooked shallots on top. Drizzle the pomegranate sauce on top. If you like, finish with a teaspoon or two of the confit oil on top. Enjoy!
Notes
The oil can be transferred to an airtight container and kept in the refrigerator for up to 4 weeks. It will have a lightly aromatic flavor but will be perfect for frying, sautéing, or using as a finishing oil on roasted vegetables or soups.If you want to make the sweet potatoes ahead of time, simply bake in the oil. Once cool, transfer the entire baking dish to the refrigerator. The next day, transfer to the oven at 300ºF and bake until warmed through, about 20-25 minutes. Remove and plate as the directions suggest.