Preheat the oven to 375 degrees F (190 degrees C).
Combine the ground beef and onion in a skillet over medium-high heat. Cook, stirring occasionally until beef is no longer pink, and the onion is translucent. Drain off excess grease, and season with salt, pepper and garlic powder.
Return to the heat, and stir in the golden mushroom and cheese soups until well blended. Heat through, and remove from stove. Transfer the mixture to a 9x13 inch baking dish. Cover the ground beef mixture with a layer of frozen French fries.
Bake for 25 to 30 minutes in the preheated oven. When the fries are golden brown, remove the casserole from the oven, and sprinkle cheese over the top. Return to the oven, and bake just until cheese has melted.