There are a few specific steps involved in making French onion green bean casserole. You will first need to caramelize the onions in a large skillet. When caramelizing onions, stir every few minutes but only once the onions start to brown. If you continuously stir them, they will never caramelize. On the other hand, make sure they don't burn!
During cooking, you can add a few drops of water to loosen the fond on the bottom of the pan. Brown sugar will help a bit with the caramelization process. Next, you need to make a béchamel or, as it's called here, a white sauce. This creamy delicious sauce will help hold the casserole together. For this step, you will need a sauce pot. Combine everything in a casserole dish, top with breadcrumbs and cheese, and you are ready to bake.
French Onion Green Bean Casserole
10
20 minutes
1 hour
1 hour 20 minutes
For the caramelized onions:
2 tablespoons vegetable oil
5 cups yellow onions, thinly sliced
1/2 teaspoon brown sugar
1/2 teaspoon salt
1 tablespoon sherry vinegar
For the white sauce:
2 tablespoons butter
2 tablespoons all-purpose flour
3 cups half and half
2 teaspoons seasoned salt
For the casserole:
2 pounds fresh green beans, trimmed
4 ounces grated Gruyere cheese
1/2 cup grated parmesan cheese
1/2 cup shredded mozzarella cheese
1 cup breadcrumbs
Pre-heat oven to 375 degrees F.
For the caramelized onions: In a large skillet on medium-high heat, add oil and onions and brown sugar. Cook, stirring every 4 or 5 minutes until they turn brown and sweet. Do not let onions turn too dark. Reduce heat if needed. Season with salt and sherry vinegar. Cook until vinegar has evaporated.
For the white sauce: On medium-low heat, melt butter in a medium sauce pan. Once butter starts to bubble, whisk in flour. Cook for 3 minutes while whisking. Slowly whisk in cold milk and seasoning salt. Simmer for 5 minutes until sauce thickens and any lumps disappear.
Bring a large pot of water to a rapid boil and blanche green beans for 3 minutes.
In a casserole dish, combine beans, caramelized onions, white sauce and Gruyere cheese.
Sprinkle parmesan, mozzarella and breadcrumbs over top of casserole.
Cover loosely with aluminum foil and bake for 30 minutes. Remove foil and continue to bake for 15 minutes.
Pro Tip: For easier prep, use thawed frozen green beans