Add dried porcini mushrooms to a 1-cup liquid measuring cup. Pour boiling water over the mushrooms to fill the measuring cup. Let stand to soften for 15 minutes. Using a slotted spoon remove the mushrooms. Strain and reserve the liquid. Coarsely chop the mushrooms.
Heat a 12-inch sauté pan over medium-high heat. Warm the oil in the pan and then add onions, carrot, fennel, and thyme, stir to combine. Once you have a good sizzle on the vegetables, turn the heat down to medium and cook for about 20 minutes or until they are soft and golden. Add the garlic and mushrooms and simmer for about 5 minutes.
Add the sausage to the pan, brown the sausage breaking it up and stirring as it browns for about 10 minutes. Add the wine and let it completely absorb, about 2-3 minutes. Then add the porcini mushroom liquid, the tomatoes, and basil. Bring to a boil and then reduce the heat, simmer for about 45 minutes or until the sauce has thickened. Taste for seasoning and add salt and pepper if needed. Remove the thyme sprigs.
Preheat oven to 375 F
Bring a large pot of water to a boil. Cook pasta according to package direction minus a few minutes - pasta should be slightly firm and chewy. Reserve 1 cup of pasta water.
Drain pasta and add it to the sauce. If it seems dry add a little of the pasta water, Stir to combine. Transfer the pasta and ragù to a 3-quart baking dish.
Add the cream evenly over the pasta. Mix the breadcrumbs and melted butter in a small bowl and then add the cheese. Stir to combine. Sprinkle the mixture over the pasta in the baking dish. Bake for 35-45 minutes or until golden brown on top and bubbling around the edges. To serve: sprinkle with parsley.