Having a versatile side dish like a vegetable gratin in your repertoire is handy this time of year. When you dress up fall vegetables with lots of flavorful ingredients and bake them with a golden crumb topping, suddenly you’ve got something special. A gratin is the perfect thing to serve with a nice rib roast, and it’s a natural for Thanksgiving—you can pretty much rest assured that everyone from Uncle Harry to Cousin Carlotta will love it. And with a big salad, a gratin makes a good Sunday night supper, too.
To make a gratin that really is that good, you need to remember a few tips. Baking vegetables (unlike roasting them) isn’t necessarily the greatest way to draw out their flavor, so if you’re going to pack them tightly into a casserole, you’ve got to add flavor. First, sauté aromatic ingredients like garlic and onions to bring out their sweetness. Next, deglaze the sauté pan to infuse your liquids with the flavor of the sautéed aromatics. Then spike the liquid with even more flavor by mixing in fresh herbs or bold-flavored ingredients such as mustard or horseradish.
The liquids you choose can also boost the flavor of your gratin. I like a combination of chicken broth and a little heavy cream. Cream is a great flavor carrier, so even if you decide to cut back on the quantity (and use more broth to compensate), don’t be tempted to leave it out altogether. For a little more interest, I sometimes spike the broth and cream with apple cider, dry sherry, or another dry wine.
The other secret to a successful fall gratin is using a little bit of potato. I find that gratins made with all squash or all sweet potato (or even a combination of root vegetables) lack structure without the potato, which holds together well when cooked and adds a bit of starch to the cooking liquid. Finally, don't forget the buttery crumb topping for the crunchy contrast.
Prepare your gratin in four easy steps
1. Sauté the aromatics to concentrate their flavor. Leeks, garlic, onions, shallots—even apples taste richer and sweeter after browning.
2. Add flavorful liquids like apple cider or sherry to the sauté pan, along with broth and cream, to deglaze the aromatics and infuse the liquids.
I3. nclude potatoes in the mix of vegetables to add structure to the gratin; use your hands to toss the vegetables with the aromatics, liquids, and cheese.
4. Make a crunchy topping of coarse breadcrumbs (use a rustic loaf), melted butter, and a little more cheese.
If you don’t want to make the entire gratin all at once, you can do several things ahead. The aromatic ingredients can be chopped and cooked, and the liquids can be combined and held in the refrigerator for several hours. You can also make your breadcrumbs and grate your cheese a day ahead. If you want to assemble the whole dish a few hours ahead, just be sure that the cooked components are completely cooled to room temperature before mixing with the vegetables. Refrigerate the assembled gratin without the topping and remove it 45 minutes before baking to get it closer to room temperature. If you’ve held the gratin for several hours, sprinkle an extra tablespoon or two of chicken broth across the top. Just before popping it in the oven, make the crumb topping and put it on.