Martha Stewart’s String Bean Casserol

Martha Stewart’s String Bean Casserol is a rich, comforting side dish made with tender green beans, creamy mushroom sauce, and a crisp golden onion topping. The casserole has a silky, savory filling balanced by fresh beans that still keep a slight bite, making every spoonful hearty without feeling heavy. This recipe is simple enough for beginner cooks but elegant enough for holiday dinners and special family meals. From start to finish, the casserole takes about 1 hour and delivers classic homemade flavor with a fresh, from-scratch touch.

Ingredients

For the Green Beans

• 700g fresh green beans, trimmed
• Salted water, for boiling

For the Creamy Mushroom Sauce

• 2 tablespoons unsalted butter
• 1 tablespoon olive oil
• 250g mushrooms, sliced
• 1 small onion, finely chopped
• 2 garlic cloves, minced
• 3 tablespoons plain flour
• 350ml whole milk
• 120ml vegetable stock
• 1 teaspoon salt
• ½ teaspoon black pepper
• 1 teaspoon soy sauce

For the Topping

• 150g crispy fried onions
• Butter, for greasing the dish

How to Make Martha Stewart’s String Bean Casserol

• Prepare the oven: Preheat the oven to 190°C or 170°C fan. Lightly grease a medium casserole dish with butter and place a shelf in the middle of the oven.
• Cook the green beans: Bring a large saucepan of salted water to a boil. Add the trimmed green beans and cook for 4 to 5 minutes until bright green and slightly tender. Drain and rinse under cold water to stop the cooking.
• Cook the vegetables: Heat the butter and olive oil in a large frying pan over medium heat. Add the mushrooms and chopped onion, then cook for 8 minutes until softened and lightly golden.
• Add the garlic: Stir in the minced garlic and cook for 1 minute until fragrant.
• Make the sauce: Sprinkle the flour over the vegetables and stir continuously for 1 minute. Slowly pour in the milk and vegetable stock while stirring to create a smooth sauce.
• Season the filling: Add the salt, black pepper, and soy sauce. Continue cooking for 3 to 4 minutes until the sauce thickens.
• Assemble the casserole: Fold the cooked green beans into the sauce until evenly coated. Spoon the mixture into the prepared casserole dish.
• Add the topping: Scatter the crispy fried onions evenly over the top of the casserole for a crunchy finish.
• Bake the casserole: Bake for 20 to 25 minutes until hot, bubbling around the edges, and golden brown on top.
• Cool and serve: Let the casserole rest for 5 minutes before serving warm.

Tips for the Best String Bean Casserole

How do I keep the green beans from becoming mushy?

Boil the beans only until slightly tender before baking. They continue cooking in the oven, so undercooking slightly helps them stay firm.

Can I make the casserole ahead of time?

Yes, assemble the casserole without the onion topping and refrigerate for up to 24 hours. Add the onions just before baking.

What mushrooms work best in this casserole?

Button mushrooms or cremini mushrooms both work well and create a rich, earthy flavor.

How do I keep the topping crispy?

Add extra fried onions during the last 5 minutes of baking or just before serving for maximum crunch.

Serving Suggestions

• Serve alongside roast turkey or chicken
• Pair with mashed potatoes and gravy
• Add to a holiday buffet table
• Enjoy with baked ham and dinner rolls
• Serve with cranberry sauce for festive meals

Storage

Room Temperature

Do not leave the casserole at room temperature for more than 2 hours after baking.

Refrigerator

Store leftovers in an airtight container in the refrigerator for up to 4 days. Reheat in the oven for the best texture.

Freezing

Freeze the casserole without the onion topping for up to 2 months. Thaw overnight in the refrigerator before reheating and adding fresh onions.

Nutrition

• Calories: 290 kcal
• Carbohydrates: 20g
• Protein: 7g
• Fat: 19g
• Saturated Fat: 8g
• Sodium: 580mg

Nutrition values are estimates and may vary depending on ingredients used.

FAQs

Martha Stewart’s String Bean Casserol

Recipe by Milli RoseCourse: Side DishCuisine: AmericanDifficulty: Easy

Servings

8

servings

Prep time

20

minutes

Cooking time

40

minutes

Total time

60

minutes

Calories

290

kcal

1

hour 

Creamy green bean casserole with mushrooms, crispy onions, and a rich homemade sauce. A classic comfort-food side dish perfect for holidays and family dinners.

Ingredients

• 700g fresh green beans, trimmed

• 2 tablespoons unsalted butter

• 1 tablespoon olive oil

• 250g mushrooms, sliced

• 1 small onion, finely chopped

• 2 garlic cloves, minced

• 3 tablespoons plain flour

• 350ml whole milk

• 120ml vegetable stock

• 1 teaspoon salt

• ½ teaspoon black pepper

• 1 teaspoon soy sauce

• 150g crispy fried onions

• Butter for greasing

Directions

• Preheat oven to 190°C (170°C fan). Grease a medium casserole dish lightly with butter.
• Bring a large pot of salted water to a boil. Cook green beans for 4–5 minutes until bright green and slightly tender. Drain and rinse with cold water.
• Heat butter and olive oil in a large frying pan. Add mushrooms and onion, then cook until softened and golden.
• Stir in garlic and cook for 1 minute until fragrant.
• Sprinkle flour over the vegetables and stir well for 1 minute.
• Slowly pour in milk and stock while stirring constantly until smooth and thickened.
• Season with salt, black pepper, and soy sauce.
• Fold the green beans into the sauce and transfer everything to the prepared casserole dish.
• Scatter crispy fried onions over the top and bake for 20–25 minutes until bubbling and golden.
• Allow the casserole to cool for 5 minutes before serving warm.

Notes

• Do not overcook the beans before baking.
• Fresh mushrooms give the sauce the best flavor.
• Add extra crispy onions just before serving for more crunch.