How to Make It
Preheat the oven to 400°.
On a parchment paper-lined baking sheet, toss the squash with the oil and salt. Arrange in an even layer and roast in the oven until tender and beginning to brown, about 40 minutes.
Meanwhile, brown the pancetta in a medium skillet until crispy and the fat has rendered, 4 minutes. Remove to a plate lined with a paper towel. Pour out all but 1 tablespoon of bacon fat and sauté the shallot over medium heat until soft and slightly caramelized, 5 minutes.
In a medium mixing bowl, combine the squash, shallot mixture and cayenne. Mash with a fork until semi-smooth. Taste for seasoning and add more salt as necessary.
Preheat the broiler. Arrange the bread on a baking sheet. Toast under the broiler until lightly browned on both sides, 2 minutes per side. Slather each piece with squash and top with the cheese and pancetta. Garnish with chives and serve immediately.