Ingredients
For the Crispy Onions (choose air fry OR fry in oil):
Air Fry Method:
- 2 Vidalia onions thinly sliced
- 1 cup buttermilk or milk
- 1 cup all-purpose flour
- 1 tsp salt
- ½ tsp black pepper
- 1 tsp paprika
- 1 tsp onion powder
- 1 tsp garlic powder
- Olive oil spray or avocado oil spray
Oil Fry Method:
- 2 large Vidalia onions thinly sliced into rings
- 1 cup buttermilk or milk
- 1 cup all-purpose flour
- ½ cup cornstarch
- 1 tsp salt
- ½ tsp black pepper
- ½ tsp garlic powder optional
- ½ tsp paprika optional
- 3-4 cups vegetable oil for frying
For the Casserole:
- 1 ½ lbs fresh green beans cleaned and trimmed
- 1 tablespoon salt
- 3 tbsp butter
- 8 ounces mushrooms sliced (button, baby bella, or cremini)
- 1 garlic clove grated
- 2 tbsp all-purpose flour
- ½ tsp salt
- ½ tsp black pepper
- 1 tsp mustard powder
- 2 ½ cups whole milk or heavy cream
- ½ cup shredded Gruyère cheese
- 1/3 cup grated Parmesan cheese
Method
Step 1: Make the Crispy Onions
Air Fry Method:
- Soak onions in buttermilk for at least 15 minutes.
- Mix flour, salt, pepper, paprika, garlic powder, and onion powder in a shallow dish.
- Drain onions, dredge in flour mixture, and shake off excess.
- Preheat air fryer to 400°F. Spray basket with oil, add onions in a single layer, and spray the tops.
- Air fry 7–10 minutes, shaking halfway, until golden. Transfer to a wire rack to cool and stay crispy.
Oil Fry Method:
- Soak onions in buttermilk 20–30 minutes.
- Whisk flour, cornstarch, salt, pepper, garlic powder, and paprika in a dish.
- Heat oil in a skillet or Dutch oven to 350°F.
- Dredge onions in flour mixture, then fry in batches for 2–3 minutes until golden.
- Drain on paper towels and season lightly with salt.
Step 2: Blanch the Green Beans
- Preheat oven to 350°F.
- Bring a large pot of salted water to a boil.
- Cook beans for 4 minutes, then transfer immediately to an ice bath to stop cooking. Drain and set aside.
Step 3: Make the Mushroom Cream Sauce
- Melt butter in a large pan over medium heat.
- Add mushrooms and cook 5–6 minutes until softened and liquid has evaporated.
- Stir in garlic and cook 30 seconds.
- Sprinkle flour, mustard powder, salt, and pepper over mushrooms. Whisk and cook for 1 minute.
- Slowly whisk in milk or cream. Bring to a boil, stirring often, until thickened (about 5 minutes).
- Remove from heat and stir in Gruyère and Parmesan until melted.
Step 4: Assemble the Casserole
- Stir green beans and half the crispy onions into the mushroom sauce.
- Spray a 9×13 baking dish with nonstick spray and pour in the mixture.
- Cover with foil and bake 30 minutes, until bubbly.
- Uncover, top with remaining onions, and bake 5 more minutes.