In a large pot, bring the broth, 4 cups water, and salt to a boil. Meanwhile, wrap the garlic, sage, rosemary, bay leaf and red chile flakes in a piece of cheesecloth and tie with a piece of twine to make a pouch. Reduce the heat to low, add the herb pouch and simmer for 10 minutes. Remove and discard pouch, then add kale and simmer for 10 minutes. Drain kale, return liquid to the pot and return to a simmer. Set kale aside. In a medium bowl, mix the two types of polenta together. With the broth mixture at a simmer, pour the cornmeal into the pot in a slow, steady stream while stirring with a wooden spoon. Keeping the heat very low, stir slowly every few minutes for about 40 minutes. If some lumps form, press them against the side of the pot to dissolve them. The polenta should be thick and creamy.

While the polenta is cooking, heat 1 tablespoon of the oil in a large skillet over medium heat. Add sausage and cook until golden brown all over. Drain and reserve.

To finish the polenta, turn off the heat, cover pot and let rest, without stirring, for 10 minutes. Remove lid and stir polenta, scraping the sides of the pot with the wooden spoon. Add reserved kale, beans, 1/4 cup of the Parmesan cheese, 1/2 cup of the parsley and remaining 2 tablespoons oil and stir gently to incorporate all the ingredients into the polenta. Cook for another 2 minutes at a simmer, continuing to stir.

To serve, top the polenta with the sausage and sprinkle with remaining parsley and Parmesan cheese.