Make-ahead green bean casserole

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Make-ahead green bean casserole

Make the mushroom sauce up to 3 days ahead (or 3 months and freeze), the fried onions 1-3 months ahead (store on counter), and the casserole can be assembled a day in advance.

Prep Time20

Cook Time20

Mushroom sauce & fried onion cook time1

Total Time1 40

Servings: larger servings

Calories: 391kcal

Ingredients

Green beans

2 lbs fresh green beans

Mushroom sauce

1.5 lbs cremini mushrooms see note about adding shiitake
2 cloves fresh garlic
2 tablespoon olive oil or shallot oil from frying
2 tablespoon butter
¼ cup flour 30 grams
1.5 cups chicken stock or vegetarian stock
1.5 cups half & half see note for using milk or heavy cream
1 tablespoon lemon juice
2 teaspoon worchestershire sauce or sub in soy sauce
½ teaspoon pepper or more to taste

Fried shallots

2 lb shallots
2 cups oil for frying like vegetable oil
salt to taste

Instructions

FRIED ONIONS: make ahead 1-3 months, store on counter

Slice the shallots thin - about 1/16th inch thick (the thickness of a wheat thin or 2 credit cards). Use a mandolin if possible so they are the same thickness and cook in the same amount of time.
Place shallots in a saucepan & cover with oil. You may need to do this in 2 batches depending on your pot size & the amount of oil you want to use. If you do it in 2 batches, you can reuse the oil.
I use a medium sized stainless steel pan. Use a high-heat oil like vegetable or avocado oil. The shallots should just float so they aren't touching the bottom of the pan (which can burn them).
Cook over high heat - the oil should be anywhere between 250℉ and 325℉. Stir occasionally and check on the color of the shallots.
Prepare drying area. You will need a metal strainer and a heat proof bowl so you can quickly drain the shallots. Line a baking sheet with several layers of paper towel to absorb oil once you remove them.
The strainer needs to be dry (water and oil don't mix). If you used the strainer for rinsing green beans, make sure to thoroughly dry it.
Remove when light-to-medium golden (not golden brown). They will continue to darken after removed as the oil and their internal heat continue cooking.
To remove, pour into a metal strainer over a heat-proof bowl. Transfer to paper towel lined baking tray and pat dry with paper towels. Salt to taste. Remove to clean paper towels to finish drying. (Extra oil makes them soggy).
You can fish them out instead of straining, but you have to do it in 1-2 passes. Even an extra 30 seconds can over cook them (see post for timeline photos).
Store in an airtight container lined with paper towel, room temperature but out of direct sunlight. Mine were still crispy 3 months later!

MUSHROOM SAUCE: make ahead 3 days (fridge) or 3 months (freezer)

Prepare vegetables & milk-mixture. Chop mushrooms into small pieces or give them a few pulses in a food processor. Dice garlic. Mix together the half & half, broth, lemon juice, worchestershire sauce, and pepper.
Add olive oil in a skillet (or use leftover oil from frying the shallots or even butter). Cook mushrooms until they release their water, then continue cooking until the mushrooms start to dry out a little.
Add garlic and continue to cook mushrooms & garlic until golden and fragrant. Season with salt.
Melt the butter in the pan with the mushrooms. Then add flour and stir to combine. Cook until it smells toasty - about 5-7 minutes. (See post for a white vs golden roux).
Add ¼ cup of the milk mixture to the hot pan. DO NOT ADD MORE! Whisk to combine. The mixture will ball up and turn into a blob.
And another ¼ cup of the liquid. Whisk to combine. Continue adding liquid in SMALL increments (adding too much at once will create lumps). Continue until the mushroom sauce is your desired thickness. You may not use all of the liquid.
Taste & adjust. Add more salt or pepper if desired. If the sauce is too thick, add more liquid (run out of your mixture? Just add more dairy or broth, no need to mix more). If it's too runny, simmer until it thickens.
Store in the fridge for up to 3 days (note that leftovers might not last as long). Or transfer to a freezer-safe container and freeze for 3 months. Thaw overnight. Sometimes dairy products can separate when frozen, but this hasn't happened to me with this mushroom sauce. If it does, reheat in a pan and whisk until recombined.

TRIM & BLANCH GREEN BEANS: make ahead 1 day

These are only made 1 day ahead because otherwise the cut ends can dry out too much. If you're using fresh green beans, you want them to be fresh!
Trim the ends off the green beans.
Heat a pot of water to boiling with about 1 tablespoon of salt per quart of water. Meanwhile, prepare a bowl with ice water (ice water IS better than cold tap water).
Add your fresh green beans to boiling water and cook for 5 minutes. They will start to soften and still be bright green. Strain and then immediate transfer to ice water for 5 minutes. Then strain and dry on paper towels.
To store: roll them up in paper towels and store in an open bag or container in the fridge.

GREEN BEAN CASSEROLE - make ahead 1 day

After you blanch the green beans, you can assemble the casserole or do it Thanksgiving morning - both seem to turn out the same.
To make ahead: mix blanched green beans with mushroom sauce and ¼ cup of fried shallots (for a little extra flavor) in your 9x13 casserole dish. Cover with foil (or a casserole dish cover, which helps for stacking pans in the already-crowded fridge).

BAKE THE GREEN BEAN CASSEROLE @ 350℉ covered in foil for 30+10 min

Bake the green bean casserole, covered with foil, for 30 minutes. Uncover it, then bake for another 10 minutes.
Remove from the oven and top with remaining fried onions.

Notes

Mushrooms: use any mix of mushrooms that you want. Cremini have a classic mushroom flavor, shiitake add less flavor but more umami (savory), and wild mushrooms usually add more earthiness.

Heavy cream, half & half, and milk:

Heavy cream: For Thanksgiving, if you will already have heavy cream around, you can use that instead of buying half & half. Leave the amount the same for a really rich casserole, or reduce it by a half-cup (per batch) and replace that with extra broth.
Milk: if you run out of half & half or heavy cream, don't worry. You can use milk. Use an extra half-cup (per batch), add 2-4 tablespoon of butter (per batch, for richness), and reduce broth by a half-cup.

Scaling the 9x13 pan:

As long as the green beans fit and can be covered with the sauce, you can use any size pan.

If you make a half-batch, use an 8x8 pan
You can add up to 50% more in a regular 9x13 pan
You can double the recipe and still use a 9x13 pan if it's a really deep, deep dish.

Baking temperatures:

You have some wiggle room to coordinate your oven on Thanksgiving day. Leaving the onions off until you take it out of the oven means it's also hard to burn the casserole!

- 300-325F: might need 45 minutes covered in foil, 15 uncovered

- 350F: 30 minutes covered, 10 uncovered

- 375-400F oven: about 20 minutes covered, 5-10 uncovered

Nutrition: the calories are calculated with all ingredients, as is, except for the frying oil. I used the calorie information for homemade fried shallots from Serious Eats and scaled it for this recipe. The nutrition is calculated for 8 servings.

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