As with any dish, ovens vary in temperature, and cooking times may be affected. So keep an eye on it and adjust the cooking time as needed.We use block cheese rather than pre-shredded cheese because it can help with the texture, as pre-shredded cheese often contains cellulose--- a substance that helps prevent clumping but can affect the melting properties of the cheese.Salt is used to bring out all the flavors of the other ingredients. Be careful with your amount, as cordon bleu cheese is already quite salty. If you rather not add any salt, you can skip the additional salt.The chicken cordon bleu casserole is done when the top is golden brown, and the cheese is melted. To check for doneness, you can insert a knife or fork into the center of the dish. If it comes out clean, the casserole is done. If there's still raw batter, put it back in the oven for a few more minutes.