Place rack in center position of oven and preheat to 350°F.
Bring a large pot of salted water (or chicken broth) to a boil. Add the green beans and simmer for 15 minutes. Drain and transfer to an approximately 2 ½-quart baking dish.
Sprinkle chopped bacon over the green beans in the baking dish. Melt the butter (in a glass measuring cup in the microwave or in a small saucepan on the stove). Stir in the brown sugar, soy sauce, garlic powder, and pepper until well combined. Pour over the green beans and bacon in the baking dish and toss until all ingredients are coated. Bake for 25 to 30 minutes until tender and heated through. Stir well and serve hot.
MAKE-AHEAD TIP: Up to two days ahead of time, cook the bacon and boil the green beans as directed. Combine them in the baking dish, cover, and refrigerate. Assemble the sauce in a small glass jar or bowl; cover and refrigerate. When it's time to cook the casserole, remove the baking dish from the refrigerator and allow it to come to room temperature while preheating the oven. Reheat the sauce in the microwave (to melt the butter) and stir well. Pour the sauce over the baking dish of green beans/bacon and toss to combine. Bake as directed.