Preheat your oven to 350°F (175°C).

In a large mixing bowl, combine the well-drained green beans, condensed cream of mushroom soup, 1½ cups of sharp Cheddar cheese, garlic powder, and black pepper. Stir until evenly coated.

Gently fold in one can of French-fried onions and any optional ingredients like cooked bacon or sautéed mushrooms.

Transfer the mixture into a greased 9x13 inch baking dish, spreading it evenly.

Sprinkle the remaining Cheddar cheese and French-fried onions over the top.

Bake in the preheated oven for about 15-20 minutes, until bubbly and golden brown.

Remove from oven, let cool for a few minutes, and serve warm.