Preheat oven to 425.
Toss green beans in bowl with 1 tablespoon olive oil and divide into twobaking sheets. Roast for 20-25 minutes until tender. Heat 1 tablespoon of oil in saucepan over medium heat. Add onions andcook until soft. Add flour and salt. Add milk and keep stirring until sauce isthick (about 4 minutes)
Once green beans are done being roasted. Preheat oven to broil.
Transfer half green beans to baking sheet then cover with half the sauce.
Layer other half of green beans and cover with the rest of the sauce.
Combine breadcrumbs and remaining oil into a small bowl and sprinkleover green beans. Place green beans in the oven on broil for 1-4 minutes, watch untilbreadcrumbs become brown at the top. Let sit for 10 minutes