In a mixing bowl, combine buttermilk, paprika, garlic powder, onion powder, salt, and black pepper. 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 smooth and slightly frothy. Set aside.

Heat a skillet over medium heat and melt butter. Dip bread slices in the egg mixture on both sides and cook in the skillet for 2-3 minutes per side until golden brown. Set aside.

Take marinated chicken from the fridge, dredge in flour, dip in buttermilk, and coat in breadcrumbs.

Heat oil in a separate skillet over medium-high. Fry breaded chicken for 5-7 minutes on each side until golden brown and cooked through. Drain on paper towels.

Assemble the sandwich by layering a slice of French toast, a piece of fried chicken, and another slice of French toast. Drizzle with maple syrup.

Slice the sandwich in half and serve warm with optional toppings.