Delicious Homemade Green Bean Casserole from Scratch

Preheat the oven to 350°F (175°C).

Place the green beans in a saucepan and add about 1/2 inch of water. Bring to a boil, then cover and steam until the beans are tender but still vibrant, around 5 minutes. Drain the water.

Combine the drained beans and mushrooms in a bowl and toss to mix well.

In a large skillet, melt butter over medium heat. Add the onion and parsley, cooking and stirring until the onion softens, about 5 to 7 minutes. Stir in the flour until smooth, then add lemon zest, salt, and pepper. Slowly whisk in the milk, stirring constantly to prevent lumps.

Stir in the sour cream and mix until smooth. Heat over medium heat until the sauce begins to simmer. Add the green beans and mushrooms, stirring to coat them with the sauce.

Remove from heat and briefly toss with half of the Cheddar cheese and half of the French-fried onions. Transfer to a 1 1/2-quart casserole dish and top with the remaining cheese and onions.