Place the chicken stock in a large saucepan. Add the garlic and cook over medium-high heat until the stock comes to a boil. Reduce the heat to medium-low and very slowly whisk in the cornmeal, whisking constantly to make sure there are no lumps. Switch to a wooden spoon, add the salt and pepper, and simmer, stirring almost constantly, for 10 minutes, until thick. Be sure to scrape the bottom of the pan thoroughly while you’re stirring. Off the heat, stir in the Parmesan, crème fraîche, and butter. Taste for seasonings and serve hot with extra Parmesan cheese to sprinkle on top.