In a large bowl, combine buttermilk, paprika, garlic powder, onion powder, salt, and black pepper. Whisk until smooth and blended, then add the chicken breasts. Cover and refrigerate for at least 1 hour or overnight.

In a shallow dish, whisk together eggs, milk, and vanilla extract until well combined. This will soak into the thick-cut bread.

Heat a skillet over medium heat and add butter. Dip each slice of bread into the egg mixture and cook in the skillet for 2-3 minutes per side until golden brown. Set aside.

Dredge marinated chicken in flour, then dip in buttermilk, and coat with breadcrumbs. Heat oil to 350°F and fry the chicken for 5-7 minutes per side until golden brown. Drain on paper towels.

Layer the sandwich: Place one slice of French toast, add chicken, top with another slice of French toast. Drizzle with maple syrup and add optional toppings.

Serve immediately for the best flavor and texture. Enjoy with fresh fruit or crispy hash browns.