Preheat oven to 220°C (200ºC fan). Spray a large baking tray with cooking spray.
Place flour in a shallow bowl and season with salt and pepper. Place eggs in a shallow bowl and whisk in water. Place panko in a third shallow bowl and stir in parmesan.
Working one at a time, dip asparagus in flour, then in egg, and finally in panko, coating well.
Place on prepared baking tray and bake until golden and crispy, 20 minutes.
