In a large dutch oven add: turkey wings, onion, celery, carrots, garlic, olive oil, 2 teaspoons of salt and 1 teaspoon of pepper.
Toss to coat.
Roast uncovered for 1 hour. (After the hour, broil for about 4-5 minutes to add some browning) Be sure to keep an eye on it!
After the hour, take the pot from the oven and place it on the stove top. Add chicken broth and thyme and bring to a full boil then reduce to medium heat and simmer uncovered for 30 minutes.
After simmering, strain everything and reserve the liquid. (place liquid in the freezer for 30 minutes so the fat will accumulate on the top then skim off the fat)
In the same pot that you cooked the wings in, add in your butter and melt.
Once the butter is melted, add in the flour and cook for 2 minutes on medium heat white stirring.
Add your skimmed liquid back to the pot, bring to a boil and then reduce to a simmer for 5 minutes. (stirring occasionally)
Serve immediately or allow to cool before storing in the freezer or refrigerator.
Notes
If you would like to deepen the color and add more "brown" to the gravy, add in 1 tablespoon of soy sauce. It won't change the taste by much at all and will add a deeper color.