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Vegan Green Bean Casserole (Dairy-Free) - Cozy, Creamy, and Crowd-Pleasing

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Prep Time 15 minutes
Cook Time 45 minutes
Total Time 1 hour
Servings: 8 servings
Ingredients Method

Ingredients
  

  • Green beans: 1.5 to 2 pounds fresh (trimmed and halved), or two 12-ounce bags frozen, or four 14.5-ounce cans (drained)
  • Olive oil or vegan butter: 3 tablespoons
  • Yellow onion: 1 small, finely chopped
  • Garlic: 3 cloves, minced
  • Cremini or button mushrooms: 12 ounces, sliced
  • All-purpose flour: 3 tablespoons (use gluten-free blend if needed)
  • Vegetable broth: 1.5 cups, low-sodium
  • Unsweetened non-dairy milk: 1 cup (oat, almond, or soy)
  • White miso paste: 1 teaspoon (optional, for umami)
  • Tamari or soy sauce: 1 tablespoon
  • Ground black pepper: 1/2 teaspoon
  • Kosher salt: To taste
  • Onion powder: 1/2 teaspoon
  • Nutmeg: Pinch (optional, but great)
  • Lemon juice: 2 teaspoons (brightens the sauce)
  • Crispy fried onions: 1.5 to 2 cups (store-bought, dairy-free)

Method
 

  1. Heat the oven: Preheat to 375°F (190°C). Grease a 9x13-inch baking dish or a similar casserole dish.
  2. Prep the green beans: If using fresh, bring a large pot of salted water to a boil. Blanch beans for 4–5 minutes until bright green and crisp-tender, then drain and shock in ice water. Pat dry. If using frozen, thaw and pat dry. If using canned, drain well and pat dry.
  3. Sauté the aromatics: In a large skillet, warm the olive oil or vegan butter over medium heat. Add chopped onion and cook 3–4 minutes until softened. Stir in garlic and cook 30 seconds until fragrant.
  4. Cook the mushrooms: Add sliced mushrooms with a pinch of salt. Cook 6–8 minutes, stirring occasionally, until they release their moisture and start to brown. Don’t rush this step—browning builds flavor.
  5. Build the roux: Sprinkle flour over the mushrooms and stir for 1 minute to coat and cook off the raw taste.
  6. Add liquids: Slowly whisk in the vegetable broth, then the non-dairy milk, stirring constantly to avoid lumps. Bring to a gentle simmer.
  7. Season the sauce: Stir in tamari/soy sauce, miso (if using), onion powder, pepper, and a pinch of nutmeg. Simmer 3–5 minutes until the sauce thickens to a creamy, gravy-like consistency. Taste and add salt as needed. Finish with lemon juice for brightness.
  8. Combine: Add the green beans to the skillet and toss to coat evenly. If your skillet isn’t large enough, mix everything in a big bowl.
  9. Assemble: Transfer to the baking dish. Smooth the top. Bake uncovered for 15–18 minutes until bubbling around the edges.
  10. Add the crunch: Remove from the oven, sprinkle the crispy fried onions evenly over the top, and return to the oven for 8–10 minutes until the onions are golden and crisp.
  11. Rest and serve: Let the casserole sit for 5–10 minutes before serving so the sauce settles and thickens slightly.