Preheat oven to 400°F.
Cook bacon in a small frying pan until crispy. Remove from pan to drain on paper towels. Reserve bacon grease.
Place green beans and onions in a large bowl. Add about 2 tablespoons of the reserved bacon grease. Sprinkle with salt and pepper, toss to coat.
Cover a cookie sheet with Reynolds Wrap® Non-Stick Aluminum Foil. Spread green beans in single layer on cookie sheet.
Roast for 20-30 minutes, or until green beans are browned and cooked. Toss with bacon and serve hot.