This Old-School French Technique Is the Secret to the Best Green Bean Casserole

published Nov 14, 2023
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Serious Eat's green bean casserole in baking dish with serving scooped out.
Credit: Photo: Joe Lingeman | Food Stylist: Jesse Szewczyk

I often prefer to make my own white sauce instead of opening a can of cream of mushroom soup for my green bean casserole recipe. It’s easy to make, but it’s even more delicious, thanks to the classic French technique of making a traditional bechamel.

A béchamel is a staple recipe in cooking and is often the base to flavorful baked dishes, such as macaroni and cheese. To make a béchamel, you start by making a roux with melted butter and flour, which will help thicken the sauce later.

Before stirring the milk into my roux, however, I infuse it with aromatics. It guarantees the tastiest, creamiest sauce that can be used in a multitude of recipes, whether it be green bean casserole, macaroni and cheese, mashed potatoes, or tuna noodle hot dish. This can be done either in a saucepan on the stove or in the microwave.

Credit: Lauren Volo

How to Infuse Milk for Green Bean Casserole 

To make a flavorful béchamel, or white sauce, for my green bean casserole, I always like to gently simmer or heat fresh herbs and spices in the milk, before combining it with the green beans. This way, the casserole comes out nice and creamy, but also incredibly flavorful. Here’s how to do it:

  • Combine 2 cups of whole milk with 1 garlic clove, 1 bay leaf, 2 thyme sprigs, and 4 whole black peppercorns in a large microwave-safe measuring cup or bowl, or add to a small saucepan. (You can also substitute with other herbs you like, such as sage or rosemary.)
  • Microwave the mixture for 2 minutes on high or heat over medium heat until steaming, but don’t allow it to boil. If you’re preparing the mixture on the stove, watch it carefully and stir occasionally.
  • Set aside for 10 minutes. Remove the aromatics with a fork or strain through a sieve and discard.
  • Prepare a roux in a separate saucepan on the stove (2 tablespoons each butter and flour). Once the roux has come together, add the warm milk mixture to the saucepan. Simmer on medium heat, whisking frequently until thickened and bubbly. Season with salt, white pepper, and a pinch of freshly grated nutmeg.