Marinate the Chicken: In a mixing bowl, combine boneless chicken thighs, buttermilk, salt, and white pepper. Ensure each piece is fully coated, then cover and let marinate for at least 30 minutes, or up to 2 hours in the refrigerator.

Heat the Oil: Fill a Dutch oven with about 1.5 inches of vegetable oil and heat to 350°F (175°C).

Prepare the Coating: Mix together self-rising flour, onion powder, garlic powder, paprika, and Tony's seasoning in a shallow bowl.

Fry the Chicken: Coat each piece of chicken in the flour mixture and fry two pieces at a time for about 7 minutes per side or until golden brown.

Make the Sauce: Combine bourbon sweet chili sauce ingredients in a small saucepan and simmer over low heat for 5-7 minutes.

Prepare the French Toast: Whisk together eggs and milk, then soak brioche slices in the mixture and cook on a griddle over medium heat for 3-4 minutes on each side.

Assemble the Sandwich: Stack fried chicken pieces between two slices of French toast, drizzle with sauce, and cut in half for serving.