- For the most part, I found frozen green beans in 12-ounce packages. If you find 10-ounce packages, I would still stick to 2 packages. I have tried the recipe with 3 (10 ounce) packages and there was not enough sauce for that many beans.
- Be sure to use frozen cut green beans, not “French” green beans (the long, stringy ones) or whole, uncut beans (you’d just have extra work cutting them).
- To substitute fresh beans, use 2 pounds of fresh green beans and start by trimming them and cutting them in half. Then, bring 4 quarts water and 1 Tablespoon salt to a boil. Meanwhile, fill a large bowl with ice and water. Cook the beans about 5 minutes, until bright green and crisp-tender. Drain the beans and immediately plunge into the ice water. Drain well before adding them to the sauce in Step 5.
- To triple the recipe for 30 to 40 people, increase the ingredients as follows: 1/2 cup (1 stick) butter 3 pounds white button mushrooms, wiped clean and sliced or broken into pieces 1 bulb garlic (9 to 10 cloves) 3 teaspoons salt and 1/2 teaspoon pepper 1 cup flour 4 1/2 cups chicken broth 4 1/2 cups heavy cream 6 (12 ounce) packages of frozen cut green beans 3 cups canned fried onions (or more if desired)
- 3x recipe instruction changes: Cook the mushrooms for about 10 minutes in Step 2 and simmer the sauce for 10 minutes in Step 3. Cook on HIGH for 2 hours or LOW for 4 hours (or until a thermometer reaches at least 165 degrees in the middle of the casserole). Add more canned onions throughout serving time if the top layer is depleted, if desired.
- The mushroom sauce may be prepared in advance, cooled, and refrigerated overnight. Increase the crock pot time to 3 hours on HIGH or 5 hours on LOW.
- If using fresh beans, they may be blanched the night before, cooled, and stirred into the cooled mushroom sauce and refrigerated overnight. Increase the crock pot time to 3 hours on HIGH or 5 hours on LOW.
- Adapted from Cook’s Illustrated Magazine, November & December 2006 issue.
To make Green Bean Casserole in the oven:
Follow the recipe as written through Step 5, but then instead of transferring the green bean mixture to a slow cooker, spread it in the bottom of a 3-quart OR a 9x13 baking dish. Sprinkle with the topping and bake at 425 degrees until the top is golden brown and the sauce is bubbling around the edges, about 15 minutes.