Preheat oven to 425F. Line a large sheet pan with foil and coat with cooking spray.

Place the sweet potatoes cut-side down on the pan. Drizzle with oil and season with salt. Roast for 15 minutes.

Move the potatoes to one side of the pan. Add the sliced onions to the other side, drizzle with oil, season with salt and pepper, and spread into an even layer.

Return to the oven and roast for another 20–25 minutes, stirring the onions once, until the sweet potatoes are completely fork-tender and the onions are softened and beginning to brown.

Transfer the potatoes to a cutting board until cool enough to handle. Drizzle the onions with honey, toss and spread back into an even layer. Roast for another 10–15 minutes, stirring once, until deeply golden and caramelized.

Remove and switch the oven to broil.

Scoop the sweet potato flesh into a large bowl, leaving the skins intact. Add the crème fraîche, butter, chives, Worcestershire sauce, and half the cheese.

Finely chop the caramelized onions and add them to the sweet potato mixture. Season with salt and pepper to taste and stir until combined.

Spoon the filling back into the potato skins and top with the rest of the cheese (enough to generously cover each potato.)

Broil for 2–4 minutes, watching closely, until the cheese is melted and browned in spots. Garnish with more fresh chives to make it pretty.