Line a baking sheet with foil. Preheat oven to 400F.

Toss onion with evoo, salt and pepper and arrange on lined baking sheet. Roast onion,stirring occasionally for 15 minutes until medium brown and soft. Add green beans to pan and stir to combine.

Continue roasting for an additional 10 minutes until beans are wrinkled and lightly browned. Remove from oven and stir garlic into beans and onions. (the heat of the pan and beans will lightly cook the garlic). Season with salt and pepper.