Instructions

1. Make the crispy onions. Preheat the oven to 475 degrees F. Combine the sliced onions, flour, breadcrumbs and salt in a bowl until well coated. Place in a single layer on a greased baking sheet and cook until crispy, about 25-30 minutes, stirring halfway through. 
2. Steam the green beans until just tender on the stove or in the microwave, set aside. 
3. Heat butter in a large skillet over medium heat. Add the shallots and cook for another 2-3 minutes until soft. Add in mushrooms and season with salt and pepper. Cook for ~10 minutes until mushrooms are browned and liquid has evaporated. 
4. Sprinkle flour over and cook for 1 minutes, then whisk in vegetable broth. Stir together and cook until thickened. Add in the milk and whisk again, then reduce heat to low and cook until bubbly. Remove from heat and add in green beans. 
5. Reduce heat to 400 degrees F. Transfer mixture to a lightly greased casserole dish (or, keep in the skillet if it’s oven-safe). Top with onions and cook another 15 minutes until browned. 
6. Remove from heat and serve immediately.