Slide a heavy rimmed sheet pan into the cold oven, set the oven to 425F, and let the pan heat with it. Give it a full 20 minutes after the oven signals it is ready.

Scrub and thoroughly dry the sweet potatoes, then slice them into even ½ inch rounds with the skin on. Blot the cut faces dry on a towel.

Toss the dry rounds with the cornstarch in a large bowl until every face looks dusty and matte.

Add the olive oil, kosher salt, smoked paprika, garlic powder, and black pepper and toss again until the coating is even and slightly slick. Cornstarch first, oil second.

Pull the hot pan from the oven and lay the rounds down in a single layer with space between them. They should sizzle on contact. Use two pans rather than crowding one.

Roast 15 minutes, flip each round, and roast another 10 minutes, until the edges are deeply browned and the rounds feel firm.

Mix the grated cheddar and parmesan together and press a small flat mound onto each round.

Return to the oven for 8 minutes, until the cheese has spread to the edges and browned into a lacy rim.

Rest the bites on the hot pan for 3 minutes so the cheese sets crisp, then lift them off with a thin spatula.

Whisk the Dijon, honey, cider vinegar, and a pinch of salt together until smooth. Scatter the sliced chives over the bites and serve with the dip.