Makes about 2 cups
Set a 2-quart saucepan over medium heat and add butter. Once butter has melted and begins to bubble, add flour and stir with a wooden spoon to incorporate and form a roux. Continue to stir until roux is dark brown, about 6 to 8 minutes. Add shallots, garlic, and thyme. Cook, stirring often, until shallots and garlic are fragrant, about 1 minute. Add Worcestershire sauce and cook until nearly evaporated, about 1 minute. Add stock and season with salt and pepper; bring to a boil, reduce to a simmer, and continue to cook until sauce has reduced and roux has been cooked out, about 20 minutes. Remove from the heat and serve immediately or set aside until ready to use.
Cook's note: You can make this in the roasting pan used to cook the turkey breast. Just add butter to the pan juices and add flour to the butter-pan juice mixture.