Heat olive oil in a large pot over medium heat.
Add diced onion, carrots, and celery; sauté for 5-6 minutes until golden at edges.
Add minced garlic, curry powder, Old Bay, salt, and pepper; cook 1-2 minutes until fragrant.
Pour in chicken broth and bring to a boil.
Add chicken breasts, cover, and cook 20 minutes until internal temperature reaches 165F.
Remove chicken with a slotted spoon and shred using two forks.
In a separate saucepan over medium-low heat, melt ghee.
Whisk in flour constantly until combined, then cook 2-3 minutes until nutty-smelling and paste-like.
Slowly pour milk into the roux while whisking constantly until smooth and thick like heavy cream.
Pour the roux mixture into the pot with broth and stir to combine.
Add shredded chicken, cooked brown rice, and baby spinach.
Cook 3-4 minutes until spinach wilts and everything is heated through.