Place clean turkey breast into 6 qt or larger slow cooker.
Chop rosemary fine and sprinkle all over turkey breast.
Zest orange and sprinkle orange zest over turkey breast as well.
Cut orange in slices and set to the side.
Season turkey breast generously with salt & black pepper.
Squeeze orange slices over turkey breast and toss them into slow cooker.
You can add orange juice if you wish.
Place lid on slow cooker, set to low. Cook for 5 hours for 4 lb. turkey breast and 6 hours for 5lb turkey breast. Check internal temperature of your turkey breast with a thermometer. Desired temperature is 165 degrees in the thickest part of the breast. (see chart in blog post for cooking times for larger sizes)
Remove to a plate, tent with foil and allow to rest for 20 minutes before carving.
If you want to brown the skin brush with canola oil and place under the broiler for 3-4 minutes. Keep and eye on it so it doesn’t burn. Allow to rest before you carve it.