Kimberly Higgins Dietitian Food Nutrition

Holiday Green Bean Casserole with Mushrooms & Onions

Green Bean casserole
Holiday Green Bean Casserole

Keep the flavors, skip the additives and preservatives

Green bean casserole is a favorite addition to the holiday table. However, the original recipe is made with canned soup, canned deep fried onions and often, canned green beans – making it high in preservatives, flavor enhancers (including MSG) and palm oil.

Fresh mushrooms and thyme

This version is made from actual mushrooms and onions that have been cooked down until they are carmelized and sweet. A traditional roux, made from butter and flour is used to thicken milk, producing a creamy béchamel sauce which binds all the vegetables. Fresh thyme enhances the flavor and because the beans are just briefly blanched before going in the casserole, they retain their bright green color and tender, not soggy, texture.

Blanched green beans are folded into the creamy mushroom sauce.

The recipe has all the creamy goodness of the traditional casserole and features the much-loved flavor combination of sweet onions, savory mushrooms and tender green beans. But it uses whole ingredients and has less fat, sodium and calories than the original. There are a few more minutes spent chopping onions and mushrooms and cooking them until they are golden and flavorful, but the end results are well worth the time! And truly, this recipe is simple and can be made days ahead of your holiday. It requires only a warm-up in the oven and is sure to please a crowd!

Green Bean casserole

Holiday Green Bean Casserole

Crisp-tender green beans coated in a creamy mushroom and onion sauce.
Course Side Dish
Cuisine American
Servings 8


  • 16 oz green beans, trimmed
  • 1 large sweet or white onion
  • 8 oz cremini or baby Bella mushrooms, sliced
  • 2 tsp fresh thyme or 1 tsp dried thyme
  • 4 tbsp butter, divided
  • 4 tbsp flour
  • 2 cups whole milk, room temperature
  • 1/2 cup chicken broth, water or milk if needed for thinning
  • salt & pepper
  • 1-2 tbsp grated parmesan cheese, if desired


  • It is necessary to blanch the green beans before starting the recipe. To do this, bring a large pot filled with water to a boil. Immerse the green beans in boiling water for 4-5 minutes until crisp-tender and bright green. Do not let the green beans get soft. While beans are cooking, prepare a bowl with water and ice. Remove the beans from the boiling water with tongs and immediately submerge them in the ice water to stop the cooking process. Once they are cooled, remove them to a paper towel lined plate.
  • In a large saute pan or dutch oven, over medium low heat, melt 2 Tbsp of butter. Add sliced onions and let onions cook slowly until softened and beginning to turn golden in color. This process will take 15-20 minutes. It's important to stir onions occasionally and lower heat if the onions are browning quickly. If onions stick, add annother tablespoon of the remaining butter.
  • When onions are cooked down, add sliced mushrooms and thyme. Cook over medium heat until mushrooms are softened and slightly golden in color.
  • Add in remaining butter (1-2 Tablespoons, depending on whether additional butter was added during the cooking of onions).
  • Add flour and stir to distribute. Cook flour over medium heat for 1 minute.
  • Slowly pour milk into vegetable and flour mixture, using a whisk to stir continuously and scrape up any browned bits from the bottom of the pan. Bring mixture to a boil to fully thicken. Switch to a spoon and stir in salt and pepper to taste (approx 1 tsp salt, 1/4 tsp pepper). If mixture is too thick, add chicken broth, water or additional milk to loosen to a creamy consistency.
  • Add blanched green beans and stir to coat.
  • Lightly spray or butter a casserole dish. Add green beans with sauce to casserole and top with a sprinkle of parmesan cheese, if desired.
  • If serving right away, heat the broiler and set casserole under the broiler for 4-5 minutes until cheese is melted and mixture is bubbling.
  • If making ahead of time, wrap casserole in tin foil and store in the refrigerator for up to 4 days. Reheat, covered, at 375 for 20 minutes. Remove foil and continue cooking 10-15 minutes or until casserole is bubbling and browned slightly.
Keyword Holiday