Add olive oil to dutch oven or cast iron skillet. Place in oven and preheat oven to 350° Fahrenheit.
Mix butter, creole seasoning, thyme and salt together. Loosen skin on the turkey breasts while still keeping it attached to the turkey. Rub 1/2 of the butter mixture underneath the turkey's skin, coating as much of the turkey as possible. Pat outside of the turkey dry using a paper towel. Coat the outside of the turkey breasts with the rest of the butter mixture.
Remove heated skillet from the oven. Place onion, orange, sage in a heap in the bottom of the skillet. Place the buttered turkey over the onion, orange and sage to roast.
Roast turkey breasts in preheated oven for 1.5 hours or until meat thermometer reads 155° when inserted into the thickest part of the breast without touching the bone. Cover with foil to prevent over browning, if necessary. Let turkey rest 15-20 minutes before slicing and serving.