Slice the shallots thinly. Heat 1/2 inch of vegetable oil over medium-high heat. Fry the shallots for 2-3 minutes until golden brown and drain on paper towels.

Boil water in a large pot, add green beans, and blanch for 3-4 minutes. Transfer to ice bath, then drain well.

Melt 2 tablespoons of butter or olive oil in a saucepan over medium heat. Sauté onions until translucent, then add garlic and mushrooms for an additional 5-7 minutes. Gradually whisk in stock and flour, cooking until thickened (3-5 minutes).

Fold the blanched green beans into the mushroom sauce, seasoning with onion powder, garlic powder, salt, and pepper as needed.

Preheat oven to 375°F (190°C). Transfer mixture to a greased baking dish, top with fried shallots and parmesan cheese.

Cover with foil and bake for 20 minutes, then uncover and bake an additional 7-10 minutes until topping is golden brown.