Preheat the oven to 425 degrees F. Bring a large pot of salted water to a boil. Add the pasta and cook as the label directs for al dente. Reserve 1 3/4 cups of the cooking water and then drain. Set aside.
Heat 3 tablespoons oil in a large saucepan over medium heat. Add the kale and garlic and cook, stirring, until the kale begins to wilt. Add 1/2 cup of water, 3/4 teaspoon salt and 1/4 teaspoon pepper and continue to cook, stirring occasionally, until the kale wilts and is crisp-tender, about 3 minutes. Transfer to a bowl and set aside.
Carefully wipe out the saucepan. Bring the half-and-half, cayenne and nutmeg to a simmer over medium heat. Cook until reduced to 1 1/2 cups, about 15 minutes. Add the cream cheese and stir until melted. Gradually whisk in the Cheddar and Havarti cheeses, a handful at a time, until all the cheese is melted and the sauce is smooth.
Add the cooked pasta and reserved cooking water to the sauce and stir to combine. Stir in the kale and season with additional salt and pepper. Pour into a 13-by-9-inch baking dish. Toss the bread crumbs, remaining 1/4 cup olive oil and a large pinch of salt and pepper in a medium bowl and sprinkle evenly over the macaroni and cheese. Bake until bubbly and lightly browned, about 10 minutes.
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