Chicken Thighs with Mashed Sweet Potato and Mirepoix

Dinner for 2

11.6oz. bone in chicken thighs,
1/2 T. minced garlic,
1 lb. peeled sweet potatoes,
2.5 oz. onion,
5 oz. button mushrooms,
1/4 c. flour,
1 tsp. pink salt,
1/2 tsp. black pepper,
1.7oz. carrot,
1.7oz celery,
1/4 tsp. ground nutmeg,
1/4 tsp. allspice,
1 tsp. thyme leaves,
1/4 c. extra light olive oil