The air conditioning in our apartment building was recently on the fritz, just as temperatures were reaching the low 90s F -- around 32 or 33 C -- so there was no way I was going to turn the oven on. But Jackie and I were looking forward to a gratin made with the fleshy stems of a big bunch of Swiss chard whose leaves had gone into a stir-fry a couple of days earlier.
So I worked out a way to put together a faux-gratin that would have the right creamy consistency with a browned, crisp top, and the right flavor: creamy again, with a modest melted cheese component plus that particular taste of browned cheese. As I said, this was to be made with Swiss chard stems, but it would have been excellent with, say, fennel or leeks (or, of course, potatoes).
I cut the chard stems into roughly three-inch lengths, boiled them in salted water until tender, chilled them in a big bowl of ice water, then let them dry in a strainer (if I'd been using potatoes, I'd have sliced them, cooked them in garlic-infused milk and not chilled them, then used that milk in the next step). I made a thickish béchamel sauce using a butter-flour roux and roughly a cup of milk, with plenty of salt, pepper and nutmeg. To this I added around 2/3 cup (loosely filled) of grated Gruyère cheese and whisked till it had melted.
That sauce and the chard would be the body of the "gratin" and wouldn't have been any different had I intended to finish it in the oven. But since the oven was to remain shut down, the dish needed a topping that would mimic the browned surface that differentiates a gratin from creamed vegetables. In the past, I've browned bread crumbs in olive oil or butter (depending on the dish) and used these as a crunchy topping for all sorts of things, notably pasta. But here I wanted to add a toasted cheese flavor too.
So I started by melting butter in a skillet and slowly browning 3/4 cup of fine breadcrumbs (made from the white of a good baguette that had exceeded its useful life) over fairly low heat, stirring often -- almost constantly in fact -- to prevent burning. When they were golden brown, I added around a third of a cup of grated parmesan cheese. At this point, I began stirring constantly: parmesan does melt in its way, but it also readily toasts. By moving the cheese and breadcrumb mixture around in the skillet, I was able to generate a crunchy, buttery, cheesy "sand" that needed only a sprinkle of salt and some pepper to be really delicious.
To make the "gratin" I mixed the cooked chard stems with the sauce (loosened with a little more milk -- you don't want it too, too cludgy, but it is safer to make it thicker than you need: it is easy to loosen it), spread the mixture into a buttered oval baking dish (for appearance's sake) and heated it gently until the chard was hot and the sauce bubbling.
I then spread the crunchy topping over the top and brought it to the table. It was pretty convincing -- I doubt that anyone would have guessed it hadn't been finished in the oven or under the broiler - but more important it was delicious in its own right. And, as a bonus, the final cooking took a small fraction of the time it would have taken in the oven -- even if I had been inclined to turn the kitchen into a steam bath that hot New York evening.