Step 1

In a large, nonstick skillet melt the butter over medium heat. Add the onion, carrot, celery and garlic and cook for 8-10 minutes, until the onion is translucent and the vegetables are lightly browned.

Step 2

Stir in the flour and cook for 2-3 minutes until the flour coating the veggies turns golden. Whisk in 1 cup of the broth, working to smooth out any lumps as it cooks and thickens. Stir in the remaining broth and water. Add the thyme and bay leaves.

Step 3

Scrape the mixture into a 6- or 8-quart slow cooker (smaller turkey breasts will fit in a 6-quart/larger will need the space in an 8-quart slow cooker).

Step 4

Season the turkey breast on all sides lightly with salt and pepper (see note below). Place the turkey in the slow cooker (breast side down if using bone-in).

Step 5

Cover the slow cooker and cook on low for 5-7 hours until the internal temperature of the turkey breast reaches at least 165 degrees.

Step 6

Carefully transfer the turkey breast to a cutting board (or 9X13-inch pan to catch any juices), tent with foil and let rest while preparing the gravy.

Step 7

Strain the liquid from the slow cooker into a saucepan. Discard the vegetables.

Step 8

Skim fat from the gravy, if needed. Bring the gravy to a simmer over medium heat and cook for 10 to 15 minutes, stirring often, until it is slightly thickened. It won't be as thick as traditional gravy but will be silky and slightly thick. For a thicker gravy, whisk together cornstarch and cold water (a tablespoon or so of cornstarch in a couple tablespoons of water) and stir the slurry into the gravy, simmering for 2-3 minutes.

Step 9

Season the gravy with additional salt and pepper, to taste, if needed.

Step 10

Slice the turkey and serve with the warm gravy.