Preheat the Oven: Set your oven to 375°F (190°C) and grease a 9x13-inch baking dish.
Mix the Base: In a large mixing bowl, combine the cream of chicken soup, cheddar soup, mayonnaise, sweet pickle relish, lemon juice, minced onion, parsley, and Worcestershire sauce. Stir until fully blended.
Assemble the Dish : Fold the thawed hash brown cubes into the prepared soup mixture, ensuring all pieces are coated evenly. Spread the mixture evenly into the greased baking dish. Sprinkle the shredded sharp cheddar cheese over the hash browns, followed by 1 cup of the Mexican Four-Blend cheese.
Add the Fish Sticks: Arrange the frozen fish sticks in a single layer on top of the cheesy hash browns. The number of fish sticks you use will depend on the size of your baking dish, but aim for full coverage.
Top it Off: Sprinkle the remaining 1 cup of Mexican Four-Blend cheese over the fish sticks for an extra cheesy finish.
Bake: Place the casserole in the preheated oven and bake for 35–40 minutes, or until the casserole is bubbly and the fish sticks are golden brown and crispy.
Serve and Enjoy: Remove the casserole from the oven, let it cool for a few minutes, and serve warm. Pair it with a simple green salad or steamed veggies for a complete meal.