Soufflé for dinner? You bet!

My daughter called me the other day and asked, "Can I go out for pizza with my friends? Wait, are you cooking tonight? What are you making?"
"Soufflé."
"What's that?" (I can't believe my daughter doesn't know what a soufflé is!!)
"It's basically eggs and cheese and some vegetables."
"Never mind--I'm coming home!"
Ah, eggs and cheese--music to a teenage vegetarian's ears! Actually, my favorite vegetable delivery method as well.
I was given courage when this recipe popped up for me by a piece on the Splendid Table (I can't seem to find the reference now, sorry) claiming that soufflés weren't all that difficult and could even wait for a bit. So I proceeded fearlessly, and although the soufflé did deflate after a bit, it was still delicious.
The recipe comes from the February 1995 Bon Appétit in a story featuring cheddar cheese. Don't tell them that I used pre-grated sharp cheddar (which is, bizarrely, cheaper than the block stuff at my local grocery store). And it features two of my favorite sleeper vegetables: parsnips (in the original recipe) and kale (because it was wilting in the fridge). The kale adds a nice bitter edge to the very sweet parsnips, so I really recommend some sort of leafy greens in this recipe. If you use something like spinach or Swiss chard, don't add it until the very end of the vegetable cooking time.

Parsnip and Cheddar Soufflé
Adapted from Bon Appétit

Serves about 6

1 lb. parsnips, peeled and sliced about 1/2 inch thick
2-3 cups water
1 bay leaf
Salt
1 bunch kale or other leafy greens, stemmed and coarsely chopped
2 oz. (4 T.) butter
1/4 c. flour
Pepper, nutmeg
6 eggs, separated (put the yolks in a small bowl and the whites in a large mixing bowl)
about 7 oz. grated sharp Cheddar
1/4 t. cream of tartar

Heat the oven to 400--don't use the convection setting. Grease a large soufflé dish. Put the parsnips, the water, the bay leaf, and a good teaspoon of salt in a large pot and set it on high heat to boil. When it comes to a boil, turn the heat to medium-high and set the timer for 15 minutes. You can stem (I usually do this with kitchen shears) and chop the kale now. When the timer has gone down to about 7 minutes left, add the kale. When the time is up, strain at least one cup of the cooking liquid into a glass measuring cup. DON'T FORGET! Drain off the rest of the water and let the vegetables cool down a bit before removing the bay leaf and then puréeing the rest in a food processor or blender.
Now get out a large-ish saucepan and melt the butter in it. Whisk in the flour and perhaps a bit of pepper and nutmeg while you're at it, and then gradually whisk in the vegetable cooking liquid. (If you forgot to save the cooking liquid, I'm sure that vegetable or chicken broth, or even milk, would be fine.) This will make a very thick sauce. Take it off the heat and add the cheese. Stir that until it melts, and then add the vegetable purée. Whisk the egg yolks until they're blended and then add a bit of the hot cheese mixture to that to temper the egg yolks. Then add the yolks back to the cheesy stuff and whisk that well. Set that aside for a bit.
Add the cream of tartar to the egg whites and beat them until they are stiff and glossy. Fold about a third of them into the cheese mixture, then carefully fold the cheese mixture into the whites. I find that a large balloon whisk worked better than a rubber scraper for this. Pour this into the soufflé dish and pop that into the oven and let it do its thing for 45 minutes. Oohh and ahh over its golden puffiness and dig in.