1 (4 to 6 pound) bone-in turkey breast, thawed completely
1/2 cup unsalted butter, softened
3 cloves garlic, minced
1 tablespoon fresh rosemary, finely chopped
1 tablespoon fresh thyme, finely chopped
1 tablespoon fresh sage, finely chopped
1 teaspoon salt
1/2 teaspoon black pepper
1 medium yellow onion, quartered
2 stalks celery, cut into large chunks
1/2 cup chicken broth
Instructions
Step 1: Prepare the Turkey. Remove the turkey breast from its packaging. Pat the skin very dry with paper towels. This helps the herb butter stick to the surface and helps the skin color better during the cooking process.
Step 2: Mix the Herb Butter. In a small bowl, combine the softened butter, minced garlic, rosemary, thyme, sage, salt, and pepper. Use a fork to mash everything together until the herbs are evenly distributed throughout the butter.
Step 3: Season the Bird. Gently loosen the skin over the turkey breast with your fingers. Rub about half of the herb butter directly onto the meat under the skin. Spread the remaining butter all over the outside of the skin, covering it as evenly as possible.
Step 4: Load the Slow Cooker. Place the onion quarters and celery chunks at the bottom of the slow cooker to act as a natural roasting rack. Pour in the chicken broth. Place the herb-rubbed turkey breast on top of the vegetables, breast-side up.
Step 5: Slow Cook. Cover the slow cooker with the lid. Cook on Low for 5 to 7 hours, or until the internal temperature reaches 165°F (74°C) when checked with a meat thermometer in the thickest part of the breast.
Step 6: Rest and Serve. Carefully remove the turkey from the slow cooker and place it on a cutting board. Tent it loosely with aluminum foil and let it rest for at least 15 to 20 minutes before carving. This allows the juices to redistribute so the meat stays moist.