Green Bean Casserole

Instructions

1. Preheat oven to 425 degrees. Line a large sheet pan with foil and coat with cooking spray.
2. In a gallon-size resealable bag, add onion and oil; seal bag and shake to combine. Add 1/2 cup flour and panko; season with salt, if desired.
3. Spread breaded onion on prepared sheet pan in a single layer. Bake, turning over every 10 minutes, until golden brown, 15–25 minutes.
4. Reduce oven temperature to 350 degrees. In a large pot over high heat, bring water to boil. Cook green beans in two batches until tender, 2–3 minutes each. Drain and set aside.
5. Melt butter in a large skillet over medium-high. Stir in mushrooms and thyme; cook until mushrooms are softened and golden brown, 4–6 minutes.
6. Reduce heat to medium-low; stir in remaining garlic, pepper and flour. Cook, stirring constantly, until a paste forms, about 1 minute. Stir in broth; continue cooking, stirring constantly, until smooth, about 5 minutes. Simmer, stirring occasionally, until thickened, about 5 minutes. Remove from heat and stir in Parmesan and parsley. Season with salt and pepper, if desired.
7. Coat a 9x13-inch baking dish with cooking spray. Add green beans and top with mushroom gravy and one-fourth of the crispy onions; gently stir to combine. Cover with foil and bake 25 minutes. Remove foil and top with remaining onion. Continue baking, uncovered, 10 minutes. Remove from oven and let cool 10 minutes.