Step 1: Preheat your air fryer and cook the French fries according to the package directions until golden and irresistible. Set aside to cool slightly. If you don't have an air fryer, bake them on a sheet pan until extra golden.
Step 2: While fries are cooking, preheat your oven to 350°F (177°C).
Step 3: In a large skillet, over medium-high heat, brown the ground beef and diced onion together. Break up the beef as it cooks. Once fully cooked, add the minced garlic and cook for 30-45 seconds until aromatic. Season generously with garlic powder, onion powder, salt, and black pepper. Drain any excess fat from the skillet.
Step 4: Stir the cream of mushroom soup and cheddar cheese soup into your beef mixture until beautifully combined and creamy.
Step 5: Transfer the beef and soup mixture into a 7x11 inch casserole dish and spread it out evenly. Layer the perfectly crispy French fries right on top. Finally, sprinkle the shredded cheddar cheese generously over the fries.
Step 6: Pop your casserole into the preheated oven and bake for 10-15 minutes, or until the cheese is melted, bubbly, and calling your name. Do not overbake to avoid dried-out beef.
Step 7: While your casserole bakes, prepare the burger sauce: In a small bowl, whisk together the mayonnaise, ketchup, mustard, pickle juice, dehydrated onions, and black pepper until perfectly smooth and creamy.
Step 8: Once the casserole is out of the oven, hot and bubbly, drizzle the irresistible burger sauce all over it just before serving. Serve immediately.