The secret to a light, airy, textbook souffle? Stop trying so hard.
You've surely heard the kitchen lore about making a souffle: Don't let one molecule of yolk get in your whites, don't open the oven door, now don't close the oven door, and for god's sake, take off your Dansko clogs ... or you'll make the souffle fall.
The reality of a souffle, however, is more robust. While light, sophisticated and worthy of folklore, souffles are easy and forgiving -- provided you whip your egg whites correctly, so let's start with that.
Learn to whip egg whites to not-quite-maximum loft. Egg whites contain a bunch of protein, which is the substance that will allow our soufflé to both rise and to set. The process starts by using the whisk or beaters to coax the tightly coiled protein strands so they relax and expand. I like to whip slowly at first, sort of the way you'd stretch to limber up your muscles before you go for a run (from what I've heard, anyway).
As you whip, you introduce air into the egg-white protein, which expands and forms little cells surrounding the air, creating a foam. The more you whip, the more the whites expand and capture air, and the creamier and firmer your foam becomes. The ideal point comes when the whites have expanded and incorporated almost to their max capacity, but they still have a bit of stretch left, so there's room for the air cells to grow. To test, pull your whisk up from the whites to create a peak. The general shape of the peak should hold, and not slump back into the rest of the whites, but the tip should flop over, rather than stand sharp and stiff. You may see this traditionally referred to as "soft peaks," but in French, they call it the "bec de perroquet," or parrot's beak, and I think it's such a useful image, though slightly loony. Once your whites get to this point, they are ready.
Which is what happens when the foam/souffle goes into the oven. The heat causes the air in the bubbles to expand, hence the souffle rises. After a few minutes in the oven, the heat will also cause the proteins to set (coagulate) and firm up, after which the souffle won't expand any more.
If your egg whites were overwhipped, they were already stretched to, or beyond, their maximum, and they've lost their elasticity. They won't be able to expand in the oven, they'll burst as the air cells inflate, the souffle will be vertically challenged, and we're back to perpetuating the myth of the finicky souffle.
By the way, this principle of whipping your egg whites so they still have room to expand in the oven is valid no matter what you're leavening: dessert souffles (as long as we're talking about baked not chilled souffles, which get their height from gelatin and whipped cream), something like a souffled pancake, and many cakes, such as angel food.
Don't fret about the yolks. Did I mention the part about not getting any yolks in your whites? The idea is that any amount of fat will inhibit the whites from whipping properly, and egg yolks are mostly fat. This is an admonishment I've heard for years and always heeded. But my cooking POV has been to avoid taking fussy steps unless they make a real difference, so I decided to see whether I've been needlessly stressing over a runaway drop of egg yolk.
Seems I have been. Here's how I tested: I took eight eggs from five random egg cartons in the fridge (this kind of accumulation happens to food writers sometimes), combined them and then divided them into two identical groups. I whipped the no-yolk group in a stand mixer (after wiping down the bowl and whisk with white vinegar, an easy way to remove grease). After about four minutes, I had lovely whites with just the right amount of sexy slouch.
I repeated the process with the second group and one variable change -- I added about 1/4 teaspoon egg yolk, the amount that could reasonably accidentally drip into your whites. And guess what? Sexy, slouchy, parrot-beaky whites! Identical!
The eggshells, however, are nonnegotiable. You do not want even tiny bits of shell in your souffle batter, so crack and separate your eggs one by one into two little bowls, and then transfer those to the main bowls. You'll think this is a fussy step also, until one of your eggs breaks in the wrong way and a shard of shell slithers into your whites.
Keep the rest simple. For the rest of the process, you're essentially making a cheese sauce that will produce a killer mac and cheese (no, not all mac and cheese comes from a box), and then stirring in the egg yolks for richness and custardy texture. Introduce this cheese sauce to the parrot's beak egg whites, and your cheese souffle is underway.
It's a blast to serve your souffle right from the oven, while it's still high above the rim of the baking dish, slightly wobbly, and of course golden brown and smelling of toasted cheese. But all souffles fall once out of the oven, so don't worry if you don't make it to the table while still at full elevation. The flavor and texture is best once the souffle has cooled just a bit, anyway.
Tip: If you love the browned exterior of your souffle more than the tender, eggy interior, bake yours in a wider, flatter dish, like a deep gratin pan. The texture will still be fluffy and light, but you'll have more surface area to brown; it will probably cook a bit quicker, too.