For the red sauce: Place a rack in the center of the oven. Heat some EVOO in a medium Dutch oven or saucepot over medium-high heat. Add the garlic, carrots, celery and onions to the pot. Sprinkle with salt and pepper, add the bay and thyme and cook to soften, 5 to 6 minutes. Next, stir in the wine and tomato paste. Add the tomatoes and crush with a potato masher or wooden spoon. Bring the sauce to a bubble and reduce the heat to a simmer and thicken, 15 minutes.
Preheat the broiler.
For the bechamel and ricotta: Melt the butter in a saucepot over medium heat and whisk in the flour for 1 minute. Then whisk in the milk and bring to a bubble. Season the sauce with salt, pepper and nutmeg. Thicken the sauce and keep warm over low heat.
Drain the spinach well and separate into small pieces. Mix together the fresh ricotta and spinach in a small bowl.
For the polenta: Bring the milk and chicken stock to a low boil. Add the polenta and season with the fennel, if using, salt and pepper. Whisk the polenta to mass, 3 minutes. Finish the polenta by stirring in 1/2 of the Parmigiano-Reggiano and the butter.
Butter a casserole dish. Add half of the red sauce, and top with half of the polenta. Pour the bechamel sauce over the polenta and dot with the ricotta cheese and spinach. Top the bechamel layer with the remainder of the polenta. Top the polenta with more red sauce and the remaining Parmigiano-Reggiano and provolone. Reserve remaining red sauce, if any, to serve on the side. Broil to set and brown, 5 minutes.