Preheat the oven to 425 degrees.
Bring a large pot of salted water to boil. Cook the pasta according to package directions until just shy of al dente (about 8 minutes, versus the 12 my box called for). Drain in a colander.
Meanwhile, in a large oven-proof skillet over medium-high heat, brown the sausage, breaking it apart with your spatula into 1-inch chunks. When golden brown all over, remove to a plate.
Add the leeks to the pan, along with the olive oil or butter. Sauté over medium heat until translucent, but not browning, 5 minutes. Add the radicchio and endive to the pan. Continue sautéing until the greens are wilted and caramelized but still partially crunchy, 5 more minutes.
Off the heat add the wine and coconut cream to the pan and stir around until it forms a creamy sauce. Mix in the stock and lemon juice, and season with ½ teaspoon salt. Carefully fold in the pasta and reserved sausage until everything is well combined.
Arrange in an even layer in the skillet, or transfer to a casserole dish. Top with the cheese, if using, and breadcrumbs.
Bake in the oven for 15 minutes, until browned on top. Allow to cool for a few minutes, then serve!