In a mixing bowl, whisk together buttermilk, paprika, garlic powder, onion powder, salt, and black pepper until combined. Add chicken breasts, coat, cover, and refrigerate for at least 1 hour.

In a shallow dish, crack eggs, pour in milk and vanilla extract. Whisk vigorously until smooth for the custard base.

Heat a skillet over medium heat and melt butter. Dip bread slices into egg mixture, coat both sides, and cook for 2-3 minutes per side until golden brown.

Set up a dredging station with flour. Retrieve marinated chicken, coat in flour, dip into buttermilk, and roll in breadcrumbs.

In a skillet, heat oil over medium-high heat. Fry breaded chicken for 5-7 minutes on each side until golden brown and cooked through.

Assemble the sandwich by layering cooked chicken between slices of French toast, drizzle with maple syrup, and add any optional toppings.

Serve immediately while warm for the best flavor and texture.