Step 1

Preheat the oven to 375 degrees F (190 degrees C). Line a baking sheet with a silicone liner (such as Silpat®).

Step 2

Place bread crumbs in a mixing bowl and pour melted butter over top. Add salt, cayenne, and Parmigiano-Reggiano cheese and mix until evenly coated. Transfer to the prepared baking sheet and arrange in an even layer. Sprinkle 1 cup Cheddar cheese over top.

Step 3

Bake in the preheated oven until golden brown, 20 to 25 minutes. Remove from the oven and let cool. Leave the oven on.

Step 4

Place sweet potatoes in a mixing bowl. Add lemon zest and juice, salt, pepper, cayenne, and melted butter; toss until evenly coated. Immediately transfer sweet potatoes into a buttered baking dish.

Step 5

Bake in the center of the oven until potatoes are very tender, about 1 hour.

Step 6

Break up the crispy, cheesy bread crumbs into very small pieces and scatter evenly over the potatoes. Gently press them into the potatoes and sprinkle remaining ¼ cup Cheddar over top.

Step 7

Return to the oven and bake until browned, 15 to 20 more minutes.

Step 8

Sprinkle with chives before serving.