Preheat your oven to 425°F (220°C). Spread the frozen waffle fries in a single layer on a baking sheet. Bake according to package instructions until crispy, usually about 20-25 minutes.
While the fries are baking, combine the shredded chicken and buffalo sauce in a medium bowl, mixing until the chicken is well coated.
Once the fries are done, remove them from the oven and sprinkle the shredded cheddar cheese evenly over the top. Return to the oven for an additional 5 minutes, or until the cheese is melted.
Remove the baking sheet from the oven and evenly distribute the buffalo chicken mixture over the cheesy waffle fries.
Top with crumbled blue cheese, sliced green onions, and diced celery if using. Drizzle with sour cream before serving.
Serve immediately while hot and enjoy your delicious nachos!