Bake the french fries according to package directions.
Meanwhile, prepare the cheese sauce. In a small saucepan, melt the butter. Whisk in the flour. Cook and continue to whisk for a minute. Slowly add the milk. Continue to cook and stir until the mixture thickens slightly - about 5 minutes. Remove from the heat and stir in cheese until completely melted and thoroughly combined. Season with salt and pepper.
To assemble the Loaded Bacon and Cheese Fries:
After the fries come out of the oven, immediately drizzle with cheese sauce. Sprinkle with bacon. Drizzle with sour cream. Sprinkle with green onions.