Seasoned beef, ketchup, mustard and cheddar bake over a French-fry base. Pre-cook the fries according to their package before layering; the covered base will soften under sauce and cheese. Pickles add a cool finishing contrast after baking. Bake the fries according to their own package before assembling the casserole. They form the base here and will soften under the beef and cheese; this method does not promise separate crisp fries after baking. Drain the cooked beef so grease does not collect around the potatoes. Spread the beef in a thin even layer rather than one central mound, then distribute the milk and cheese across it. Add pickles after baking to retain their texture. If a crisp potato side is important, cook an extra separate tray for serving rather than moving the casserole layers or relying on a longer bake that could dry out the beef.