Preheat oven to 350 degrees F (175 degrees C).

Roast in the preheated oven for 1 hour; baste turkey breast with remaining butter mixture. Return to oven and roast until the juices run clear and an instant-read meat thermometer inserted into the thickest part of the breast, not touching bone, reads 165 degrees F (65 degrees C), about 30 more minutes. Let turkey breast rest 10 to 15 minutes before serving.

While turkey is resting, transfer pan drippings to a skillet.
Skim off excess grease, leaving about 1 tablespoon in skillet. Place skillet over low heat; cook and stir shallot in turkey grease until opaque, about 5 minutes. Melt 1 tablespoon butter in skillet with shallot and whisk in white wine, scraping any browned bits of food from skillet. Whisk in chicken stock and flour until smooth. Bring to a simmer, whisking constantly, until thickened. For a creamier, lighter gravy, whisk in half-and-half.