Sprinkle chicken with salt. In batches, add chicken to pot and cook 3 to 5 minutes per side or until deep golden brown. Transfer chicken to plate.

Add mushrooms to pan; cook 8 to 10 minutes or until deeply browned, stirring occasionally. Transfer mushrooms to bowl with pancetta.

Preheat oven to 250 degrees F.

Add carrot and chopped yellow onion to pot. Cook 5 minutes or until onion is lightly browned, stirring occasionally.

Add garlic, tomato paste and black pepper; cook 1 minute, stirring constantly.

Add about 1 cup of wine to pan and cook 1 minute, scraping bottom of pan with wooden spoon.

Stir in remaining wine. Add chicken and any accumulated juices on plate, and arrange chicken in an even layer, as much as possible. Add thyme and bay leaf; heat to boiling over medium-high heat. Cover pot with lid and transfer to oven. Cook 40 minutes.

Remove from oven; transfer chicken to plate. Strain cooking liquid through a fine-mesh strainer into a 4-cup measuring cup or bowl; discard solids. Put cooking liquid back in pot.

In small bowl, mash together flour and butter with a fork (it should look like very dry cookie dough).

Heat cooking liquid to boiling over medium-high heat; whisk in flour mixture. Reduce heat to medium and simmer 10 minutes or until thickened, stirring occasionally. The sauce should be glossy and thick enough to coat the back of a spoon, but not too thick and goopy.

Stir in pearl onions (if using), pancetta and mushrooms. Add chicken and any accumulated juices, cover, reduce heat to low and cook 5 minutes or until everything is heated through. Serve garnished with parsley.