From the roundup: 24 Thanksgiving Dinner Recipes Classic Enough to Please Every Table
This roasted garlic and Parmesan green bean casserole is what I make when I want the classic on the table but cannot bring myself to open a can of cream of mushroom soup. The sauce is a real bechamel, which sounds fancier than it is: butter, flour, warm milk, and half-and-half whisked together on the stove for about six minutes until thick. Roasted garlic and freshly grated Parmesan go in at the end, and the whole thing tastes nothing like the version from a can.
Total time runs about 80 minutes, but most of that is the garlic roasting in the oven at 400 degrees while you do other things. The active work, blanching the beans, making the sauce, and folding everything together, takes closer to 25 minutes. Then it bakes at 375 degrees for 25 to 30 minutes with store-bought crispy onions on top. No frying, no extra dishes.
I almost always assemble this the night before Thanksgiving. The sauce and beans go into the baking dish, covered and refrigerated, and I add the onion topping right before it goes in the oven. One less thing to think about on a morning that already has too many moving parts.
Why you will love this
- The bechamel comes together in one saucepan and the roasted garlic does most of the flavor work, so it is not complicated scratch cooking.
- Roasting a full head of garlic at 400 degrees mellows any sharpness out of it completely, so the sauce tastes rich without being harsh.
- Fresh beans blanched for exactly 3 minutes stay bright green through the oven bake, not the dull olive color you get with canned.
- The whole casserole can be assembled up to 24 hours ahead, just hold the onion topping until right before baking.
- Serves 8 generously, and the leftovers reheat well with a handful of fresh crispy onions scattered on top.
Tips for success
- Warm the milk and half-and-half before adding them to the roux. Cold dairy poured into hot butter and flour almost always causes lumps, and fixing a lumpy bechamel is annoying.
- Pat the blanched beans completely dry before folding them into the sauce. Any water left on them will thin the bechamel and you will end up with a watery casserole.
- Do not add the crispy onion topping until right before the dish goes into the oven, whether you are baking it fresh or from the refrigerator. Onions added too early steam instead of crisp.
- Pull the casserole when the sauce is actively bubbling around the edges, not just warm in the center. If the center looks still, give it another 5 minutes. The sauce needs to be hot all the way through to set properly as it rests.
If your sauce turns out thin or lumpy
- Thin sauce usually means the beans were not dried well enough after blanching, or the milk was added too fast. Whisk over medium heat for another minute or two before pulling it off the stove.
- Lumps happen when cold dairy hits a hot roux. If you catch it early, keep whisking over medium heat and most lumps will smooth out. A quick pass with an immersion blender also works.
- The sauce should coat the back of a spoon thickly before you fold in the beans. If it slides right off, it is not ready and the finished casserole will be soupy.
- Freshly grated Parmesan melts into the sauce much more smoothly than pre-shredded, which often has anti-caking coating that makes the sauce grainy.
Substitutions
Frozen cut green beans work well here and skip the blanching step entirely. Just thaw them and pat them very dry before adding to the sauce. Gruyere or sharp white cheddar can replace the Parmesan if that is what you have, though the flavor will be a little different. To lighten the sauce slightly, you can use all whole milk instead of the milk and half-and-half combination.
For a gluten-free version, swap the all-purpose flour for a 1-to-1 gluten-free flour blend in the same amount, and use gluten-free crispy fried onions on top. The sauce behaves almost identically.
Make-ahead and storage
Assemble the casserole through the step where the sauced beans go into the baking dish. Cover it tightly and refrigerate for up to 24 hours. When you are ready to bake, scatter the crispy onions on top and bake as directed at 375 degrees, adding 5 minutes to the bake time if it is going in cold from the refrigerator.
Leftovers keep covered in the refrigerator for up to 3 days. Reheat in a 350-degree oven for 15 to 20 minutes, and add a small handful of fresh crispy onions for the last 5 minutes so you get some crunch back. This dish does not freeze well once assembled: the sauce separates and the beans turn soft when thawed.
Roasted Garlic and Parmesan Green Bean Casserole
Ingredients
Equipment
Method
- Preheat your oven to 400 degrees. Slice the top off a whole head of garlic to expose the tips of the cloves. Set it cut-side up in a small oven-safe dish, drizzle with 2 teaspoons of olive oil, and cover tightly with foil. Roast for 40 to 45 minutes until the cloves are completely soft and golden when you press them. Set aside to cool. Turn the oven down to 375 degrees for the casserole.
- While the garlic roasts, blanch the green beans. Bring a large pot of well-salted water to a boil. Add the trimmed beans and cook for 3 minutes exactly. Drain immediately and plunge them into a bowl of ice water. Leave them there for 2 minutes, then drain and pat completely dry. If using frozen beans, skip this step.
- Once the garlic is cool enough to handle, squeeze the soft cloves out of their skins into a small bowl. Mash them into a rough paste with a fork.
- In a large saucepan, melt the butter over medium heat. Add the flour and whisk constantly for about 1 minute until the mixture smells slightly toasty and looks like a pale paste. This cooks out the raw flour flavor.
- Slowly pour in the warmed milk and half-and-half, whisking constantly as you add it to prevent lumps. Keep whisking over medium heat until the sauce thickens enough to coat the back of a spoon, about 5 to 7 minutes. It should be thick but still pourable.
- Remove from the heat. Stir in the roasted garlic paste, grated Parmesan, salt, pepper, and nutmeg. Taste the sauce and adjust salt if needed.
- Add the blanched green beans to the saucepan and fold them gently into the sauce until evenly coated. Pour everything into a greased 9×13 baking dish and spread it level. At this point you can cover and refrigerate the dish for up to 24 hours if making ahead.
- Scatter the crispy onions in an even layer over the top. Bake at 375 degrees for 25 to 30 minutes, until the sauce is bubbling around the edges and the onions are deep golden brown. Let it rest for 5 minutes before serving.
Notes
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