A 3 quart or larger is sometimes used but the baking is not always as even. To whip the egg whites their highest, you can use wire whips or a mixer. The bowl you use should be cool, not warm and if you have a copper bowl that is placed in the refridgerator beforehand, all the better. A spatula is great for folding the egg mixtures together as it is flat and not harsh. The oven should be properly heated before placing the souffle inside and make sure you have finely chopped all added ingredients such as onion before pouring the souffle mixture into the baking pan to ensure a perfect rise.
Nothing is more unappealing in a souffle than lumps.
You can cut down on the whipping time by adding a pinch of salt to the egg whites. You will know when the egg whites have been beaten enough when they don't tip easily out of the bowl when you tip it. Once the souffle mixture is in the dish you can use a spatula or knife and trace a circle 1 inch deep about one inch from the side of the dish. This will let the souffle rise more in the middle, making it look like a top hat. And lastly, make sure you serve the souffle right out of the oven for the most impressionable effect.