Pat dry chicken thighs. Season with salt and Cajun seasoning.
Mix flour, paprika, cayenne, white pepper, granulated onion, and garlic powder. Dredge chicken in mixture.
Heat oil in a skillet. Fry chicken until golden brown on both sides—4 to 5 minutes each.
Remove chicken. Sauté onions for 2-3 mins. Add garlic and thyme, cook for 3-5 mins. Set onions aside.
Add butter to the pan. Stir in seasoned flour, forming a paste. Whisk in chicken broth and milk until smooth.