Preheat oven to 375F/190°C Spray a 9" x 12" lasagna-type glass or crockery casserole dish with olive oil or non-stick spray.
Add the salt to a large pot of water and bring to a boil. Trim stems from the kale, then cut the kale into ribbons about 1/2 inch wide. When the water starts to boil add the kale, lower heat so the water is gently boiling, and cook kale 5-6 minutes. Drain kale into a colander in the sink and let it continue to drain while you prepare other ingredients. (I used a salad spinner to gently spin the water from the cooked kale and then let it continue to drain.).
While the kale is cooking, heat the oil in a large heavy frying pan, squeeze sausage out of the casings, and saute until the sausage is cooked through and nicely browned, breaking it apart with the turner as it cooks. When the sausage is done, add the pasta sauce, dried basil, and ground fennel. Stir to combine and let the sauce simmer 20-25 minutes, or until it's thickened and the liquid is reduced.
In the casserole dish, layer 1/2 the drained kale, sprinkle 2 T Parmesan, 1/2 the sauce, and 1 cup mozzarella. Repeat with another layer of kale, Parmesan, sauce, and mozzarella. Cover the dish with foil and bake for 20-25 minutes, then remove the foil and bake another 15-20 minutes, or until the casserole is bubbling and cheese is starting to brown.
Let the mock lasagna sit for about 5 minutes before you cut it. Serve hot.
I am guessing this freezes well, although I haven't thawed out any of my frozen servings yet.