Step 1

In a large deep skillet, heat the olive oil. Add the sausage and cook over moderately-high heat, breaking up the meat with your spatula into small crumbles, until well-browned and cooked through, about 5 minutes. Add the panko and crushed red pepper and season with salt. Cook the breadcrumbs, stirring occasionally, until beginning to brown, about 2 minutes. Stir in the sage. Scrape the breadcrumbs into a bowl and keep warm. Wipe out the skillet.

Step 2

In a large pot of salted boiling water, cook the pasta until just al dente. Drain, reserving 1 cup of pasta water.

Step 3

Meanwhile, in the large deep skillet, melt the butter. Add the flour and cook over moderate heat, whisking constantly, until the roux begins to smell toasty, about 2 minutes. Whisk in the half-and-half and simmer over moderately-low heat until the sauce begins to thicken, 3 to 5 minutes. Do not let the half-and-half come to a boil. Whisk in the pumpkin purée, grated parmesan, lemon juice, garlic, and nutmeg until smooth. Season with salt.

Step 4

Fold the pasta and kale into the sauce and season with salt. Cook over moderately-low heat, stirring until the pasta is coated and the kale has wilted, about 2 minutes. If the sauce is too thick, gradually add the reserved pasta water.

Step 5

Spoon the pasta into shallow bowls and sprinkle with the sausage breadcrumbs. Garnish with shaved parmesan and freshly ground black pepper. Serve right away.