Remove 6 tbsp buttermilk and set aside. To remaining buttermilk, add salt and whisk until dissolved. Cut chicken in 8 pieces (2 legs, 2 thighs, cut each breast in half). Submerge chicken in buttermilk brine. Cover and refrigerate for 1 hour.
In a bowl, whisk together flour, thyme, pepper, garlic powder and baking powder. Add reserved buttermilk and toss with fingertips to form pea-sized crumbs.
Drain chicken and transfer to breading, 2 pieces at a time. Pack breading onto chicken firmly.
Heat 4-5 cups vegetable shortening or peanut oil to 375°F It should be about 3/4 deep in the pot. Place chicken into hot fat, skin side down. The temperature will drop to about 300°F; maintain the temperature at 310-315°F Cover pot and cook 8-10 minutes; check chicken after 4 minutes to ensure even browning, and move pieces around if needed. After 8-10 minutes, turn pieces over; cook another 6-8 minutes until the second side is also golden brown.
Remove chicken and drain on paper towels. Allow to drain and cool 5-10 minutes before serving.