Soak the dried mushrooms. Place the porcinis in a small bowl, then cover with room temperature water. Allow to soak for 10 minutes, then drain and finely chop.
Brown the sausage. Heat 2 Tbsp olive oil in a large pan with deep sides over medium-high heat. Add sausage and cook, breaking up with a wooden spoon, until browned on all sides, about 4-6 minutes. Use a slotted spoon to transfer the sausage to a small bowl, leaving the renderings in the pan.
Cook the mushrooms. Add 2 thinly sliced shallots and 3 chopped garlic cloves, then cook until transluscent and fragrant, about 3 minutes. Add 3 Tbsp butter to the pan. When melted, add sliced or chopped mushrooms. Cook, stirring occasionally, for 5 minutes, or until browned on all sides.
Deglaze the pan. Pour in 1 cup red wine, then cook 1-2 minutes, or until wine has reduced by about half.
Add remaining ingredients. Add 2 Tbsp tomato paste, the crushed tomatoes, 2 Tbsp thyme leaves, ½ tsp cinnamon, 1 tsp Kosher salt, ½ tsp freshly ground black pepper and the chopped rehydrated porcini mushrooms. Stir well, then return the browned sausage to the pan and add ½ cup water.
Simmer the ragu. Bring the sauce to a boil, then lower the heat to a simmer. Cook for at least 30 minutes, though longer is okay. Stir occasionally and check to make sure the heat isn't too high (otherwise the bottom will burn).
Serve immediately. Remove the bay leaf, taste and adjust seasoning as needed, then serve immediately over polenta or pasta. Garnish with grated Parmesan cheese and extra thyme leaves.