1. Preheat oven to 375°F (190°C) and grease an 8×8 baking dish.

2. Blanch fresh green beans in boiling salted water for 3–4 minutes, then drain and rinse under cold water.

3. In a skillet over medium heat, melt butter and sauté onion until translucent, about 3 minutes.

4. Add mushrooms and cook 4–5 minutes until softened.

5. Stir in flour to form a roux, then slowly whisk in milk and cream until sauce thickens, about 3–4 minutes. Season with salt, pepper, and garlic powder; stir in cheese if using.

6. Toss blanched beans and half of the crispy onions with the sauce in the baking dish and sprinkle the rest on top.

7. Bake for 18–22 minutes until bubbly and golden. Let rest 5 minutes before serving.

8. For the canned option, mix drained canned green beans, condensed soup, milk, garlic powder, salt, and pepper in a bowl.

9. Layer half of the fried onions in the dish, pour the mixture over them, top with remaining onions, and bake 20–22 minutes until bubbling.

10. Allow to cool slightly before serving; garnish with parsley or extra onions if desired.