Place the stock and dried mushrooms in a saucepan and bring to a low boil. Lower the heat and reconstitute. Remove the mushrooms with a slotted spoon and chop.
Bring a large pot of water to a boil, salt it, add the pasta and cook until al dente. Drain, reserving a little of the pasta cooking water.
While the pasta is working, heat the butter in a large skillet over medium heat. Add the cremini (or portobello) mushrooms and bay leaf and increase the heat to medium-high. Cook, stirring occasionally, until the mushrooms darken, 7 to 8 minutes. Add the kale (or swiss chard), shallots and garlic; season with salt, pepper and nutmeg. Cook for about 7 minutes longer, then stir in the wine. Add the chopped reconstituted mushrooms and all but 1/4 cup of the mushroom infused stock (the grit settles to the bottom of the pan as the mushrooms reconstitute). Stir in the cream and cook to reduce and thicken. Toss the pasta with the sauce, adding the reserved pasta cooking water if the sauce is too thick to coat the pasta nicely. Garnish with the sage and serve with the cheese.