Ingredients

The following ingredients have 10 Servings
  • 2 pounds fresh green beans
  • 2 tablespoons unsalted butter
  • 1 medium yellow onion (thinly sliced)
  • 16 ounces baby bella mushrooms (thinly sliced)
  • 3 tablespoons all-purpose flour
  • 2 cups whole milk (a lower fat milk may curdle, so swap at your own risk; for more decadence, use part half-and-half)
  • 1 teaspoon kosher salt
  • ½ teaspoon black pepper
  • 1/8 teaspoon ground nutmeg
  • 1 tablespoon sherry vinegar
  • 1 cup shredded cheddar cheese or gruyere cheese*
  • 1 1/2 cups fried onions (store bought or homemade; to make your own, see blog post above; about 3 ounces)

Instruction

  • Trim the green beans and cut into 1-inch pieces (don’t be tempted to cut them larger than this, or your green beans will turn out too firm). Add them to a 5 or 6-quart slow cooker.
  • Melt the butter in a wide saucepan over medium heat. Add onion and mushrooms. Cook, stirring occasionally, until the onion is soft and golden and the mushrooms brown and have given up their liquid, about 12 minutes.
  • Sprinkle the flour over the top. Cook, stirring constantly, for 1 to 2 minutes more, until all of the flour turns golden and no white bits remain. The vegetables will seem dry.
  • Slowly add the milk a few splashes at a time, stirring between each addition to prevent lumps from forming. Increase the heat to medium high. Stir in the salt, pepper, and nutmeg. Cook and stir, allowing the sauce to bubble gently, running a wooden spoon or rubber spatula along the bottom of the pan. Continue cooking and stirring for 6 minutes, then stir in the sherry vinegar. Cook 2 to 4 more minutes, until the sauce has thickened to resemble a creamy gravy. It should be clearly thicker than it was when you started, but still be loose enough to easily coat the green beans.
  • Pour the sauce over the green beans.
  • Stir to combine. Cook on LOW for 3 to 5 hours, until the green beans are pleasantly tender but still have a bit of crispness (i.e. are done but not mushy). The amount of cook time you need will vary based upon your slow cooker and your preference for how al dente you like the green beans. I recommend checking at the 3-hour mark to gauge their progress. We like our green beans pretty crisp, so I only let ours cook a little beyond 3 hours. If at 3-hours you'd like your green beans more done, give the casserole a stir, recover, and keep cooking until they reach your desired texture.
  • Five minutes prior to serving, stir in the cheese. Recover, turn to WARM, and let cook 5 minutes to melt the cheese.
  • Immediately before serving, if desired, transfer the green beans and sauce to a serving dish. Sprinkle the fried onions over the top (if you will be serving right out of the slow cooker, remove the lid, then sprinkle the onions on top of the green beans in the slow cooker). Enjoy hot!