Clean and pat dry the chicken thighs.
Marinate chicken in buttermilk, salt, and white pepper for at least 30 minutes.
Heat vegetable oil in a Dutch oven to 350°F for frying.
Mix self-rising flour with onion powder, garlic powder, and paprika in a bowl.
Coat marinated chicken in the seasoned flour mixture.
Fry chicken in hot oil until golden brown and cooked through, about 7 minutes per side.
Simmer apricot preserves, honey, and sriracha to make a thickened sweet chili sauce.
Whisk eggs with milk and a pinch of spices; soak brioche slices in this mixture.
Fry soaked brioche slices in a pan until golden and crisp.
Assemble sandwich by placing fried chicken between two French toast slices and drizzle with apricot chili sauce.