A lighter sauce
Maximum clean cauliflower flavor
A simple, foolproof cooking method
Cauliflower gratin should be a lighter alternative to the rich, starchy classic made with potatoes. Yet most of the recipes I’ve tried model themselves on that heavy, potato-based template: Cauliflower florets (which have been either boiled or steamed first) are arranged in a baking dish and inevitably buried under a stodgy, flour-thickened, cheesy cream sauce. I had an entirely different dish in mind: a cauliflower gratin with tender florets covered in a velvety sauce that boasted clean cauliflower flavor and was satisfying without the heft.
Trim and Fit
I started by figuring out the best way to prepare the florets. Cauliflower florets with some of their stem left on look pretty but cook unevenly because the stem is more dense than the floret. Fortunately, I had an easy way to trim the stems and create same-size florets. I first removed the core from the head of cauliflower and then cut the head into ½-inch-thick slabs. This made it easy to trim the stems, leaving flat florets about 1½ inches tall. These florets would cook evenly and, because of their flat shape, would also layer neatly in the gratin dish. I found that it took a full two heads’ worth of cauliflower to fill a standard 13 by 9-inch baking dish.
Making the Most of the Cauliflower
Step 1. Prep Core
Cut out each core, halve it lengthwise, and slice it thin crosswise. Reserve for sauce.
Step 2. Cut Slabs
Slice each head into ½-inch-thick slabs.
Step 3. Prep Stems
Cut stems from slabs to create flat, 1½-inch-tall florets. Slice stems thin and reserve with sliced cores for sauce.
Precooking the florets is typical of most recipes and for good reason; cooking them through from start to finish in the sauce would take far too long. In fact, the actual goal of baking the casserole is not to cook the cauliflower but to marry the flavors of sauce and cauliflower. But what was the best method of precooking them? Boiling the delicate florets was too aggressive; the jostling made them fall apart. I also gave roasting a try. While this approach imparted a nice toasted, nutty flavor, once I combined the florets with the sauce (a placeholder version for now) and baked the dish for about 15 minutes, I found that the nuttiness detracted from the clean flavor profile I wanted—not to mention that the browned pieces muddied the gratin’s appearance. And so I settled on the gentle technique of steaming. I simply loaded my cauliflower florets into a steamer basket and cooked them in a pot over simmering water until a paring knife slipped in and out of them with no resistance.
It was time to move on to the bigger challenge: the sauce. I continued to search for recipes that didn’t call for heavy or rich thickeners, such as a béchamel or lots of eggs, and at last found a few unique approaches to try. One featured a sauce made simply of cream thinned with chicken broth in a 2:1 ratio. It sounded lighter than the flour- or egg-thickened sauces, but sadly it was too thin (and too chicken-y). Another skipped liquids altogether and opted to combine the florets with just cheese and spices, plus a bread-crumb topping. The flavor was clean like I wanted, but the dish didn’t come together into a cohesive gratin.
Out of ideas, I began browsing cauliflower recipes beyond gratins. A dish from chef Dan Barber of Blue Hill at Stone Barns in New York caught my eye. It featured pan-roasted cauliflower nestled in a sauce made of nothing more than cauliflower cooked in milk and water and then pureed with some of the cooking liquid. His recipe takes advantage of the fact that, unlike most vegetables, cauliflower is relatively low in fiber, particularly the insoluble fiber that is resistant to breaking down. This gives cauliflower the unique ability to blend into an ultracreamy puree without any cream.
What if cauliflower became my sauce, too? It would be creamy but not too rich, with the benefit of adding another layer of the starring vegetable’s flavor. Furthermore, it occurred to me that I wouldn’t need to buy a third head; I could likely use the stems and cores I had been throwing out. Even if I augmented these scraps with a couple of cups of florets, I would still have plenty of florets for the casserole.
I simmered the stem-core-floret mixture in a few cups of water until soft, and then I poured the pot’s contents into a blender and pureed them until silky-smooth. I poured this sauce over the steamed florets layered in the dish and baked the gratin just until the sauce bubbled around the edges.
I was off to a good start, but the sauce was a bit thin and (not surprisingly, given that the cooking liquid was water) tasted too lean. Adding a little cornstarch improved the consistency. As for amping up the richness without muting flavor or making the sauce too heavy, I found that 6 tablespoons of butter added to the simmering cauliflower and water —this was the simplest approach, and it all would get blended together anyway—improved matters greatly, and the butter’s sweet flavor complemented the cauliflower perfectly.
But there was still room for a little more depth and creaminess. I feared that adding cheese might move the sauce into the heavy, gloppy category, but I was happy to discover that ½ cup of grated Parmesan, which I added to the blender, lent a complementary salty richness without weighing the dish down. For more complexity, I added dry mustard, cayenne, and nutmeg. Tossing the florets with the puree so they were fully and evenly coated before they went into the baking dish ensured that there was sauce in every bite.
Stacked in My Favor
At this point, all my gratin needed was a classic bread-crumb-and-cheese topping for some texture, flavor, and color, so I toasted panko bread crumbs in butter until they were golden and then tossed them with some Parmesan. A sprinkling of minced chives over the finished gratin enlivened its appearance.
Before I was done, I made one more improvement for efficiency’s sake. Did I really need two pots, one to steam the florets and one to simmer the sauce? For my next test, I put the stem-core-floret mixture, water, and butter in a Dutch oven and arranged my steamer basket, filled with the bulk of the florets, right on top of the mixture before adding the lid. When the florets in the basket were cooked through, I removed the basket and replaced the lid so the sauce mixture could continue to simmer. My double-decker setup was a success.
With that, I had an easy cauliflower gratin that was good enough to require a second helping and light enough to guarantee that there’d be room for it.