Other Healthy Green Bean Casserole

3  tablespoons		canola oil, divided
1		medium sweet onion, (half diced, half thinly sliced), divided
8  ounces		mushrooms, chopped
1  tablespoon		onion powder
1-1/4  teaspoons		salt, divided
1/2  teaspoon		dried thyme
1/2  teaspoon		freshly ground pepper
2/3  cup		all-purpose flour, divided
1  cup		low-fat milk
1-1/2  fl. oz.		dry sherry, (see Ingredient Note)
4  cups		pound frozen French-cut green beans
1/3  cup		reduced-fat sour cream
3  tablespoons		buttermilk powder, (see Ingredient Note)
1  teaspoon		paprika
1/2  teaspoon		garlic powder

Tip: Click on the ingredient links to learn the nutritional information for all the Other Healthy Green Bean Casserole ingredients. The serving size for any ingredient in Other Healthy Green Bean Casserole may be adjusted using the nutrition facts serving size calculator. Use it to help cut calories, carbs and more from your recipes.

Preheat oven to 400°F. Coat a 2 1/2-quart baking dish with cooking spray.
Heat 1 tablespoon oil in a large saucepan over medium heat. Add diced onion and cook, stirring often, until softened and slightly translucent, about 4 minutes. Stir in mushrooms, onion powder, 1 teaspoon salt, thyme and pepper. Cook, stirring often, until the mushroom juices are almost evaporated, 3 to 5 minutes. Sprinkle 1/3 cup flour over the vegetables; stir to coat. Add milk and sherry and bring to a simmer, stirring often. Stir in green beans and return to a simmer. Cook, stirring, until heated through, about 1 minute. Stir in sour cream and buttermilk powder. Transfer to the prepared baking dish.
Whisk the remaining 1/3 cup flour, paprika, garlic powder and the remaining 1/4 teaspoon salt in a shallow dish. Add sliced onion; toss to coat. Heat the remaining 2 tablespoons oil in a large nonstick skillet over medium-high heat. Add the onion along with any remaining flour mixture and cook, turning once or twice, until golden and crispy, 4 to 5 minutes. Spread the onion topping over the casserole.
Bake the casserole until bubbling, about 15 minutes. Let cool for 5 minutes before serving.