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Slow cooker green bean casserole on a patterned platter.

Slow Cooker Green Bean Casserole

This Slow Cooker Green Bean Casserole is a great mix of convenience and from-scratch cooking and won't take up any oven space.
Course Side Dish
Cuisine American
Prep Time 5 minutes
Cook Time 2 hours 20 minutes
Total Time 2 hours 25 minutes
Servings 10 servings (1 cup each)
Calories 280kcal



  • In a large skillet or Dutch oven, melt butter over medium-high heat until foaming subsides. Add mushrooms, garlic, 3/4 teaspoon salt, and 1/8 teaspoon pepper. Cook until the mushrooms have released most of their liquid, about 5 to 7 minutes.
  • Stir in flour and cook for one minute. Whisk in broth, scraping up any brown bits from the bottom of the pan. Bring to a boil, whisking constantly.
  • Reduce heat to medium. Whisk in cream and simmer until the sauce has thickened, about 5 minutes. Season to taste with salt and pepper.
  • Meanwhile, cook the beans in the microwave according to the package instructions (or microwave on HIGH power for 4 to 5 minutes; let stand 1 minute before removing from the microwave). Drain well (I like to use a salad spinner to spin them dry).
  • Add the green beans to the pot with the mushroom sauce and toss until evenly coated. Transfer the beans and sauce to a crock pot.
  • Cook on HIGH for 2 hours or LOW for 4 hours or until a thermometer inserted in to the middle of the casserole reaches 165 degrees. Top with canned fried onions immediately before serving.



  1. Mushrooms: Use fresh mushrooms to make a quick from-scratch cream of mushroom sauce.
  2. Frozen green beans: To substitute fresh beans, trim and chop 2 pounds of green beans. Blanch the beans in 4 quarts of boiling salted water for about 5 minutes, then drain well and plunge immediately in to an ice bath to stop the cooking.
  3. Fried onions: To substitute bread crumbs for the canned fried onions, pulse 4 slices hearty white bread (torn into pieces) in a food processor or blender. You will have about 3 cups of crumbs. Stir in 3 tablespoons melted butter or olive oil and fry in a large skillet over medium-high heat until browned. Sprinkle over the casserole just before serving.
  4. Yield: This recipe makes about 10 cups of casserole, enough for 10 1-cup sized, side dish (you'll be able to feed more than 10 people depending on how many sides you have at Thanksgiving).
  5. Storage: Store leftovers covered in the refrigerator for up to 4 days.
  6. Make ahead: You can make the mushroom sauce up to 2 days before. Cool and refrigerate. Since the sauce will be going in cold, increase the crockpot time to 3 hours on HIGH or 5 hours on LOW.


Serving: 1cup | Calories: 280kcal | Carbohydrates: 12g | Protein: 3g | Fat: 25g | Saturated Fat: 14g | Trans Fat: 1g | Cholesterol: 58mg | Sodium: 315mg | Potassium: 207mg | Fiber: 1g | Sugar: 1g | Vitamin A: 632IU | Vitamin C: 4mg | Calcium: 30mg | Iron: 1mg