From-Scratch Green Bean Casserole for Thanksgiving
This From-Scratch Green Bean Casserole is a fresh take on a classic Thanksgiving favorite. Instead of relying on canned soups, it uses crisp green beans and a homemade mushroom sauce…
Tip: save now, cook later.This From-Scratch Green Bean Casserole is a fresh take on a classic Thanksgiving favorite. Instead of relying on canned soups, it uses crisp green beans and a homemade mushroom sauce topped with golden, crunchy fried onions. It’s simple but feels like a special side dish that brings a comforting warmth to the table.
I love making this casserole because it’s so much more flavorful when you make everything from scratch. The green beans stay bright and snap just right, and the creamy mushroom sauce has a depth that you just can’t get from a can. Plus, those crispy fried onions on top add the perfect finishing touch that everyone always asks about.
For me, this casserole is all about sharing and tradition. I like to make it a day ahead so the flavors can really come together, and then pop it in the oven before dinner. It’s always one of those dishes that sparks happy conversations and fills the kitchen with a cozy, holiday smell that feels like home.
Key Ingredients & Substitutions
Fresh Green Beans: Using fresh beans gives you a crisp texture and vibrant color. If fresh aren’t available, frozen green beans work too—just thaw and drain well before using.
Mushrooms: Cremini mushrooms add earthiness but button mushrooms are fine substitutes. Finely chopping them helps create a smooth, rich sauce.
Dairy: Whole milk and heavy cream make the sauce creamy and silky. For a lighter option, try using half-and-half or a mix of milk and Greek yogurt, but add yogurt off-heat to avoid curdling.
Crispy Fried Onions: These add essential crunch. You can buy them ready-made or make your own by thinly slicing onions, dipping in flour, and frying until golden.
How Do You Make the Creamy Mushroom Sauce Thick and Smooth?
The sauce is a key flavor and texture element here. Follow these steps for the perfect creamy mushroom sauce:
- Cook onions and mushrooms slowly to release their flavor and moisture.
- Add flour to coat the veggies and cook it for a couple of minutes to avoid a raw flour taste.
- Whisk in milk and cream gradually so the sauce stays smooth without lumps.
- Keep stirring over medium heat until thickened—this usually takes 5 minutes.
- Season well with soy sauce for depth, plus salt and pepper.
Taking your time with this step means your casserole will be rich but not thin or runny. If your sauce gets too thick, stir in a splash of milk to loosen it.
Equipment You’ll Need
- Large pot – for boiling green beans quickly and evenly.
- Large skillet – perfect for sautéing onions and mushrooms for the sauce.
- Whisk – helps you smoothly mix flour, milk, and cream without lumps.
- 9×13-inch baking dish – roomy enough to bake and serve the casserole.
- Slotted spoon or strainer – useful for draining green beans after blanching.
Flavor Variations & Add-Ins
- Swap green beans for asparagus or broccoli for a fresh twist and different texture.
- Add cooked crumbled bacon for a smoky, salty punch.
- Mix in shredded cheddar or gruyère cheese for extra creamy richness.
- Stir in sautéed shallots or leeks for a sweeter onion flavor.
From-Scratch Green Bean Casserole for Thanksgiving
Ingredients You’ll Need:
- 2 pounds fresh green beans, trimmed and cut into 2-inch pieces
- 3 tablespoons unsalted butter
- 1 small yellow onion, finely chopped
- 2 cloves garlic, minced
- 8 ounces cremini or white mushrooms, finely chopped
- 3 tablespoons all-purpose flour
- 1 cup whole milk
- 1 cup heavy cream
- 1 teaspoon soy sauce or tamari
- Salt and freshly ground black pepper, to taste
- 1 ½ cups crispy fried onions (homemade or store-bought)
Time You’ll Need:
This recipe takes about 15 minutes to prep and cook the green beans and mushroom sauce, plus 20-25 minutes baking time in the oven. Plan for around 45 minutes total.
Step-by-Step Instructions:
1. Prepare the Green Beans:
Bring a large pot of salted water to a boil. Add the green beans and cook for 4-5 minutes until they are bright green and just tender. Drain them and immediately plunge into a bowl of ice water to stop the cooking. Drain again and set aside.
2. Make the Mushroom Sauce:
In a large skillet, melt butter over medium heat. Add the chopped onion and sauté until it becomes soft and translucent, about 3-4 minutes. Add the minced garlic and chopped mushrooms, cooking until the mushrooms release their moisture and become tender, about 6-8 minutes.
Sprinkle the flour over the mushroom mixture and stir well to coat everything evenly. Cook for 1-2 minutes while stirring to cook out the raw flour taste.
Slowly whisk in the milk and cream, stirring constantly until the sauce thickens and coats the back of a spoon, about 5 minutes. Stir in the soy sauce and season with salt and pepper.
3. Assemble and Bake:
Mix the drained green beans into the sauce until everything is combined. Transfer the mixture to a greased 9×13-inch baking dish and spread it out evenly. Sprinkle the crispy fried onions evenly on top.
Bake in the preheated oven at 350°F (175°C) for 20-25 minutes, until bubbly and the onion topping is golden brown and crisp. Let the casserole cool slightly before serving.
Can I Use Frozen Green Beans Instead of Fresh?
Yes, frozen green beans work well! Just thaw and drain them thoroughly before using to avoid excess moisture in the casserole.
How Can I Make My Own Crispy Fried Onions?
Slice onions very thin, toss them in flour and a pinch of salt, then fry in hot oil until golden brown and crisp. Drain on paper towels before topping your casserole.
Can I Prepare This Casserole Ahead of Time?
Absolutely! Assemble the casserole without the fried onions, cover, and refrigerate for up to 24 hours. Add the onions just before baking for the best crunch.
How Should I Store Leftovers?
Keep leftovers in an airtight container in the refrigerator for up to 3 days. Reheat gently in the oven to preserve the crispy onion topping as much as possible.