Preheat oven to 400F, scrub the sweet potatoes well, and puncture them with a fork in a few places. Bake the potatoes for about 45 to 60 minutes, or until very soft and tender.

Allow the potatoes to cool enough to handle them, slice them in half vertically, and scoop out the flesh into a large bowl, and discard the skins.

To the large bowl with the sweet potato flesh, add all the remaining ingredients from the Sweet Potato Base section.

Stir everything together with a wooden spoon or potato masher.

Transfer the mixture into a 2.5-quart baking dish that's been sprayed with cooking spray, and smooth the top lightly with a spatula.

If you're making this in advance, stop now, cover tightly with plastic wrap or foil, and refrigerate for up to 24-36 hours.

Turn the oven heat to 375F.

If desired, toast the nuts in a dry skillet over low heat, tossing them constantly for 1-2 minutes, or until fragrant.

Add the nuts and all remaining ingredients from the Topping section to a medium bowl and toss with a spoon to combine.

Evenly sprinkle the topping over the sweet potato base, and bake uncovered for about 20-25 minutes, or until the top is golden and crisp.

Optionally garnish with fresh herbs and serve immediately.