Add the salt to a pot of water and bring it to a boil. Add in the noodles and cook according to package instructions.
While the noodles are cooking, start browning the sausage in a large saute pan over medium heat. Break up any large chunks. Add in the minced garlic and crushed red pepper flakes. Stir to combine.
Drain the cooked pasta into a colander and return the noodles to the pan. Add in the sausage mixture and kale and stir to combine. Let the heat from the noodles and sausage wilt the kale.
Pour half of the baked ziti mixture into a 13x9 inch baking dish. Sprinkle 1 cup of cheese on top. Pour the other half of the baked ziti mixture into the pan and top with another cup of cheese, making sure to spread it evenly. You can add extra cheese to the top if you'd like. You can also sprinkle on a little extra red pepper flakes.
Place the pan into the oven and bake for 15-20 minutes, or until the cheese on top is starting to brown and the baked ziti is heated through. Serve and enjoy.