Grow and Multiply Your Pans

• To increase the size of your casserole, buy or borrow the largest baking pans you can, or use additional pans. Visit restaurant supply stores to see what's available. Or, buy inexpensive foil or plastic pans at the grocery. Plastic pans are more sturdy than foil, but you can only use them at oven temperatures below 400 degrees Fahrenheit. Foil pans can go into a hotter oven, but they are very flimsy and tear easily. Both pans bake more evenly and safely if you place them on metal baking sheets.

Scaling Recipes

• While increasing the amount of ingredients in a recipe doesn't work well with breads or cakes, it does work with casseroles. To convert a recipe, use a ready-made converter or do the math yourself. Divide the number of servings you want, 20 for instance, by the number of servings the recipe normally makes, say, 10. Use that number, 2 in this case, to multiply the amount of each ingredient. For strongly flavored ingredients or additions such as baking powder, use a smaller multiplier such as only using 1.5 instead of 2 when increasing the amounts of these ingredients.

Do This, Not That

• Cooking casseroles for a crowd doesn't mean crowding more ingredients into your normal pan. The casserole won't cook properly and may spill all over your oven -- doubling the number of pans you use or using a large pan are better options. However, you can't just double the cooking time when doubling a recipe in a larger pan. Instead, add about 25 degrees to the temperature, check for doneness at the normal cooking time and give the casserole an extra five or 10 minutes if it's still not done.

Cook Ahead Safely

• Many casseroles can spend three to four days in the refrigerator or two to three months in the freezer before cooking, allowing you to assemble the dishes ahead of time and bake them together in the oven prior to serving. Let frozen casseroles thaw overnight in the refrigerator and check on the casseroles after cooking with an instant-read thermometer to ensure that they reach at least 165 F. Casseroles that you can make ahead include enchiladas, chili, chicken casseroles and egg casseroles.