Preheat your oven to 450°F. Spread the frozen fries in a single layer on a large rimmed baking sheet. Bake according to package directions until golden brown and extra crispy, about 20 to 25 minutes.
While the fries bake, heat the cooking oil in a skillet over medium heat. Add the chicken and cook for 4 to 5 minutes per side, or until fully cooked through.
Add the butter, buffalo sauce, garlic powder, and onion powder to the skillet. Stir until the butter melts and the chicken is fully coated. Simmer for 2 to 3 minutes.
Remove the crispy fries from the oven and sprinkle half of the pepper jack and Monterey Jack cheese over the top.
Spoon the buffalo chicken over the fries, then finish with the remaining cheese. This layering helps the Buffalo Chicken Fries stay extra cheesy and flavorful.
Return the pan to the oven and bake for 5 more minutes, or until the cheese is melted and bubbly.
Remove from the oven and drizzle with extra buffalo sauce and ranch dressing.
Finish with blue cheese crumbles and sliced green onions. Serve immediately while hot.