In a small mixing bowl, add butter, garlic, onion powder, paprika, Italian seasoning, ginger powder, salt, pepper and mix until combined. Loosen skin of the turkey.
Spread half of the butter mixture under the skin of the turkey and spread half all over the top of the turkey.
Secure skin tightly with toothpicks, if necessary.
Coat a large crockpot (6 quart or larger) with oil.
Line the bottom with onion slices and celery sticks.
Pour broth.
Place the garlic herb butter-coated turkey on top of the veggies.
Cover and cook on Low heat for about 6 hours or until an inserted thermometer in the thickest part of the meat reads 165 degrees F.
Transfer the turkey breast to a baking tray, lined with aluminum foil.
Optional step: Broil in oven for 4-5 minutes or until top is golden brown and crispy.
Transfer to a cutting board.
Cover with aluminum foil and let it rest for about 10 minutes.
While the turkey is resting, use the leftover liquid from the slow cooker to make gravy.
Run it through a fine mesh sieve. Discard the solids.
Melt butter in a nonstick saucepan over medium heat.
Add flour and whisk everything together until combined.
Cook until mixture is light brown.
Pour 1 cup of strained drippings from slow cooker plus broth.
Cook while constantly whisking until gravy is thickened to your liking.
Use a sharp knife to cut turkey into thin slices and serve this gravy alongside it or drizzled on top. Enjoy!