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A big rectangular white pan is full of green beans. You can see lots of caramelized onions and roasted mushrooms in this gluten free green bean casserole. There are also big pillows of cheesy, creamy sauce dolloped on top.
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5 from 2 votes

Gluten Free Grown Up Green Bean Casserole

This updated version of gluten free green bean casserole is full of mushrooms, caramelized onions, and creamy cheese. Classic flavors reimagined make for a fun new holiday treat.
Prep Time20 mins
Cook Time40 mins
Total Time1 hr
Course: Side Dish
Cuisine: American
Servings: 10
Author: Mirlandra Neuneker


  • 2 pounds frozen whole green beans thawed
  • 1 tsp. salt
  • 16 oz cremini or baby Portobello mushrooms
  • ¼ cup olive oil
  • 1 Tbsp. soy sauce
  • 2 tsp. balsamic vinegar optional see note
  • 3/4 tsp. coarsely ground black pepper
  • 1 large sweet onion sliced
  • 3 Tbsp. salted butter
  • ½ tsp. salt
  • 8 oz cream cheese
  • ½ cup parmesan cheese grated
  • 3 Tbsp. milk


  • Preheat oven to 400 F.
  • Cut the mushrooms into halves or if they are larger into quarters. Combine with thawed and drained green beans in a 9”x13” casserole dish.
  • In a small bowl whisk together olive oil, soy sauce, balsamic (if using) and pepper. Drizzle over the bean mixture.
  • Roast beans, uncovered for 30 minutes stirring once half way through.
  • While the beans are roasting, prepare the onions.
  • Trim the ends of the onion and remove the skin layers. Cut in half and slice each half into thin slices.
  • Melt butter in a large skillet and add onions and salt. Cook stirring frequently until the onions start to soften. Turn the heat down to medium-low and put the lid on for about 10 more minutes until the onions are tender. Sprinkle with a bit of extra black pepper if desired and remove from heat.
  • Microwave the cream cheese until it is very soft and starting to melt, about 30 seconds. In a medium mixing bowl beat together softened cream cheese, parmesan cheese and milk with a hand mixer on medium speed.
  • When the beans have cooked 30 minutes and are tender crisp remove from oven and scatter the onions on top. Spoon mounds of the cheese mixture over the beans and return to the oven for 6-8 minutes until heated through.


Adding the balsamic vinegar gives the beans a bright grown up flavor that some people love. If you do not like balsamic vinegar omit it. My favorite way to have this is without the vinegar.
If you wish to use fresh green beans I suggest giving them a quick blanch in boiling water just to take the raw edge off before roasting.