Place chicken stock, heavy cream, salt, pepper and nutmeg into a medium non-stick saucepan and heat over medium heat until hot. Keep warm on a low flame.
Prepare and measure out the remaining polenta ingredients but do not add yet.
Clean broccoli rabe of tough outer stem, then cut into individual stalks. Place them into a large bowl and cover with ice water. Set aside. This will help remove bitterness.
In a large skillet, cook pancetta with the olive oil over medium heat until crisp. Remove cooked pancetta to a small bowl with a slotted spoon.
Keep pan at medium heat and add garlic and cook one minute. Add thyme and cook one more minute.
Add the chicken stock and heat to a simmer.
Drain the broccoli rabe and add to the pan. Cover and gently simmer until cooked.
Remove the broccoli to a platter and increase the heat on the pan and reduce the liquid to one quarter cup. Pour this over the broccoli rabe.
While the broccoli cooks, heat the polenta liquid to hot and add the polenta and semolina flour.
Stir and cook over medium heat until thick, about two to three minutes.
Stir in the Fontina and Parmesan cheese and taste for seasoning. Add salt and white pepper as needed.
Stir in the butter until it is melted into the mixture.
To serve, pour polenta onto a platter, place broccoli rabe around the edges and top with the cooked pancetta.