From-Scratch Green Bean Casserole

Steps

1. Heat the oven to 350°F (175°C) and

   butter (how to grease and flour a pan)

   Grease and flour a pan Coat a pan with fat (and sometimes flour) so baked goods release cleanly. 1. Rub a thin layer of soft butter or shortening into every corner with a paper towel, or use baking spray.2. For cakes, add a spoonful of flour, tilt and tap the pan until it is coated.3. Turn the pan over and tap out the extra flour.4. For chocolate cakes, use cocoa instead of flour so there is no white film. Done when: Every surface, corners included, is lightly coated with no bare spots or thick clumps. How to grease and flour a baking pan: mistakes to avoid

   a 9x13-inch baking dish.
   350°F
2. Bring a large pot of water to a

   boil (how to boil)

   Boil Heat liquid until big bubbles rise and break all over the surface. 1. Use a pot big enough that the water fills it no more than three quarters.2. Cover it to boil faster, over high heat.3. Salt pasta or vegetable water once it boils.4. Add the food, stir, and bring it back to a boil before you start timing. Done when: A rolling boil keeps bubbling hard even when you stir. Safety: Turn pot handles toward the back of the stove, and drain pasta into a colander in the sink, pouring away from you. Steam burns fast: lift lids and foil away from your face, tipping the far edge up first.How to boil water for pasta and vegetables: mistakes to avoid

   and add 1 tablespoon of salt. Fill a large bowl with ice and cold water.
3. Blanch (how to blanch)

   Blanch Cook vegetables briefly in boiling water, then chill them in ice water so they stay bright and crisp. 1. Fill a big bowl with ice and water.2. Bring a large pot of salted water to a rolling boil.3. Add the vegetables in small batches so the boil comes back fast.4. Cook just until bright and barely tender, often 1 to 3 minutes.5. Lift them into the ice water, then drain once cold. Done when: The color is vivid and the vegetable bends a little but still snaps. Safety: Lift food out with a slotted spoon or spider instead of tipping the pot.How to blanch vegetables: mistakes to avoid

   the green beans in the boiling water until bright green and just crisp-tender.
   ⏱ Blanch beans: 5 min
4. Drain the beans in a colander and tip them into the ice water. Once cold, drain again and pat dry with a towel.
5. Melt the butter in a large skillet over medium-high heat. Add the mushrooms and cook, stirring now and then, until their liquid cooks off and they start to brown.
   ⏱ Brown mushrooms: 8 min
6. Add the onion, garlic, salt, pepper and nutmeg and cook until the onion is soft.
   ⏱ Soften onion: 4 min
7. Sprinkle the flour over the vegetables and stir until no dry flour shows.
   ⏱ Cook flour: 1 min
8. Slowly stir in the broth, then the milk and cream, scraping the bottom of the pan as you go.
9. Simmer (how to simmer)

   Simmer Cook liquid just below a boil, with small bubbles breaking the surface now and then. 1. Bring the liquid up over medium-high heat.2. As soon as bubbles rise steadily, turn the heat down.3. Adjust until only a few small bubbles break the surface every second or two.4. Stir now and then and check that it hasn't crept back to a boil. Done when: You see lazy, small bubbles, not a rolling boil. A "bare" simmer has just a bubble here and there. Safety: Steam burns fast: lift lids and foil away from your face, tipping the far edge up first.How to simmer: mistakes to avoid

   , stirring, until the sauce is thick enough to

   coat a spoon (how to coat the back of a spoon)

   Coat the back of a spoon A simple test for when a sauce or custard has thickened enough. 1. Dip a spoon into the sauce and lift it out.2. Turn it over and look at the back.3. Draw a line through the sauce on the spoon with your finger.4. If the line stays clean and the sauce doesn't run into it, it is ready. Done when: The sauce clings in an even, opaque layer and your finger line holds. Safety: Let the spoon cool for a second before you touch it; custards should reach 160°F.How to tell when a sauce coats a spoon: mistakes to avoid

   .
   ⏱ Thicken sauce: 5 min
10. Take the skillet off the heat.

    Fold (how to fold)

    Fold Combine a light mixture (whipped cream, beaten whites) or chunky add-ins into a batter gently, so it stays airy. 1. Put the lighter mixture on top of the heavier one, or add the flour or chips.2. Cut a rubber spatula straight down through the middle to the bottom of the bowl.3. Sweep it across the bottom and up the side, then turn it over on top.4. Turn the bowl a quarter turn and repeat.5. Stop as soon as no streaks remain. Done when: There are no dry streaks or white blobs, and the mixture still looks light and puffy. Safety: Batters with raw eggs or flour aren't safe to eat raw.How to fold ingredients into a batter: mistakes to avoid

    in the green beans and 1/2 cup of the fried onions, then spread it all in the baking dish.
11. Bake until the sauce bubbles around the edges.
    350°F⏱ Bake: 20 min
12. Scatter the remaining 1 1/2 cups of fried onions over the top and bake until they are a shade darker and crisp. Watch closely; they scorch fast.
    350°F⏱ Bake topping: 7 min
13. Let the casserole stand for a few minutes so the sauce settles, then serve.
    ⏱ Settle: 5 min

Tap an underlined word for how to do it, or see all techniques.

Tips

• Shortcut version: skip the homemade sauce and stir two 10.5-oz cans of condensed cream of mushroom soup with 3/4 cup milk instead. Use three 14.5-oz cans of cut green beans, drained, in place of the fresh beans. Bake the same way.
• Frozen cut green beans work too: thaw them, pat them dry and skip the blanching.
• Use vegetable broth for a vegetarian casserole.

Storage

Refrigerate leftovers within 2 hours, up to 4 days. Reheat covered in a 350°F oven for 20 to 25 minutes, until hot in the center.

Make ahead

Assemble without the fried onions up to 1 day ahead, cover and refrigerate. Bake it cold, covered, for 20 minutes, uncover and bake about 15 minutes more until bubbling, then add the topping and finish as written.

How long leftovers keep, and freezing and reheating: leftovers and storage. In season: green beans (June to September).