Preheat oven to 450. Spray 2 10×15 baking pans or 1 12×17 baking pan with cooking spray.
Cut filets into serving size portions, rinse and pat dry with paper towels.
In a shallow bowl, mix milk and egg together. Whisk until egg and milk are blended.
In another shallow bowl mix Bisquick, parmesan cheese, salt and pepper with a fork until fairly smooth and uniform (no clumps of Bisquick or cheese).
Dip filets first in the egg/milk mixture, then in the Bisquick/cheese mixture, then arrange on the prepared baking pans.
Spray filets lightly with cooking spray.
Bake at 450 for 10 to 12 minutes or until golden brown. If filets are thick, you may want to put the under the broiler for a few minutes to crisp up the tops.
