Close up of Green Bean Casserole in a casserole dish, fresh out of the oven
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5 from 5 votes

Green Bean Casserole

Recipe video above. The most amazing creamy mushroom sauce smothering tender green beans, topped with crispy fried onions! The perfect green bean casserole with the right ratio of sauce to beans, well flavoured silky, creamy sauce with the perfect thickness and the perfect delicately crunchy onions! See notes for best way to MAKE AHEAD!
Prep Time15 mins
Cook Time1 hr
Course: Western
Cuisine: American, Thanksgiving
Keyword: Green Bean casserole, green bean recipe, Thanskgiving sides, vegetable sides
Servings: 8 - 12
Calories: 210.86kcal
Author: Nagi


  • 750g/ 1.5lb green beans , trimmed and halved

Crispy Fried Onions:

  • 2 large yellow onions , peeled, halved and thinly sliced (or 3 medium)
  • 1/4 cup (35g) flour (plain/all purpose)
  • 2 tbsp panko breadcrumbs (Note 1)
  • 1/2 tsp salt
  • 1/4 tsp black pepper
  • 4 cups / 1 litre (approx) vegetable oil , for deep-frying (or peanut, canola oil Note 2)

Creamy Mushroom Sauce:

  • 3 tbsp (50g) butter , unsalted
  • 360g /12 oz mushrooms , chopped 1cm / 1/3" pieces
  • 3/4 tsp salt
  • 1/4 tsp black pepper
  • 2 garlic cloves , minced
  • 3 tbsp (35g) flour (plain/all purpose)
  • 1 1/2 cups (375ml) vegetable or chicken broth/stock , low sodium
  • 1/2 cup (125ml) cream , heavy/thickened
  • Pinch nutmeg (or sprinkle of freshly grated)



  • Boil the green beans for 3 minutes until just tender (or to your taste), then drain and run under cold tap water (to stop cooking further). You could also steam.
  • Transfer to clean tea towel and pat dry. Set aside.

Crispy Onions:

  • Line tray with 3 - 4 layers paper towels.
  • Toss onions with flour, panko, salt and pepper.
  • Heat about 2cm / 3/4" oil in a heavy based skillet over medium high heat. Dip the end of one onion in - it should sizzle satisfyingly immediately.
  • Add some onions, not too many (see video), then fry for 1 1/2 minutes or until LIGHT golden brown.
  • Transfer to tray, spreading out (don't pile up). (Note 3)
  • Repeat with remaining onion (5-6 batches). Set aside to cool, DO NOT cover.

Creamy Mushroom Sauce:

  • Melt butter in a skillet over medium high heat. Add mushrooms and cook for 1 minute.
  • Add salt and pepper, cook until mushroom starts to soften (1.5 minutes) then add garlic and cook for 1 minute until garlic is golden.
  • Turn heat down to medium, add flour and mix until you can't see flour anymore.
  • While stirring constantly, gradually pour in half the broth. When flour lumps are dissolved, pour in remaining broth and cream, stir.
  • Add nutmeg, stir.
  • Cook for 5 minutes, stirring casually at first then regularly as it thickens, until sauce thickly coats back of wooden spoon and you can draw a path across it (see video). Sauce will not thicken further in oven.

Assemble & bake:

  • Preheat oven to 350°F / 180°C (160°C fan).
  • Pour beans into pot they were boiled in (or use bowl). Pour over Mushroom Sauce, stir.
  • Pour into 2.5 quart / 2.5 ltr casserole dish (Note 4), smooth surface.
  • Sprinkle with onions (might not use all!), then bake for 15 minutes until bubbling on the edges and the onions are deep golden. CHECK at 10 minutes to ensure onions are not burning (Note 5).
  • Serve immediately! (See notes for make ahead)


1. Panko breadcrumbs - larger pieces than normal breadcrumbs so you get much more satisfying CRUNCH! Asian aisle of most supermarkets nowadays, though cheaper in Asian stores.
2. Oil - any high heat neutral flavoured oil fine here. Do not use olive oil (low smoke point).
3. Onion frying
  • Will crisp bit more when cool, and fully crisp and brown in oven. Important to drain excess oil to ensure oven crisping (if soggy with oil, may not crisp).
  • Store bought French Fried Onions or Crispy Fried Onions (Asian aisle) - for an easy way out, use store bought onions. Sprinkle on dish then bake!
  • Makes more than you need - some practice runs plus snacking!
  • Alternative topping - Frying FAIL?! It's the big day, and you've had a frying disaster…. Don't fret! Melt some butter and mix into 3/4 cup panko with 1/4 cup parmesan and pinch of salt. Sprinkle and bake 20 minutes or until golden. SO GOOD!
4. Dish shape - better to use one that is flatter rather than deep, so you can maximise surface area for crunchy onions! Large skillet ideal, 9x13" / 23 x 33" glass pan is too large.
5. Onions browning too quickly - turn oven down, cover loosely with foil for remaining bake time. Then remove foil for last few minutes to crisp onions. This is why it's important to only fry onions until LIGHT golden - so they are deep golden and crispy once baked!
6. Make ahead - best way: cook beans and make sauce per recipe. Cover sauce immediately, cool, then store both in fridge up to 3 days (possibly longer, I just did 3 days). Fry onions the day before, cool completely before placing in a container. Do not refrigerate! On the day of, mix the beans with sauce, place in baking dish, COVER then bake 10 to 15 minutes to heat up. Remove cover, top with onions then bake for 10 minutes to crisp the onions up and make them golden!
7. Source: Recipe adapted from Alton Brown via Smitten Kitchen.
8. Serving size - really depends on how many other sides you have! Conservatively, this will easily serve 8 - 12 with say 3 or 4 other side options (ie one big scoop per person). If this was the only vegetable side, I would say it serves 5 people (150g/5oz beans per person).
Nutrition is for 8 people, assumes onions that are used for topping has 2 tbsp oil which I think is a reasonable estimate (given onions don't absorb oil).


Calories: 210.86kcal | Carbohydrates: 18.78g | Protein: 5.73g | Fat: 14g | Saturated Fat: 9.08g | Cholesterol: 31.67mg | Sodium: 447.33mg | Potassium: 435.17mg | Fiber: 3.74g | Sugar: 5.37g | Vitamin A: 996.74IU | Vitamin C: 14.65mg | Calcium: 60.99mg | Iron: 1.77mg