Preheat the oven to 350°F (175°C).
In a large skillet, brown the ground beef over medium heat, adding the diced onion and minced garlic.
Once the beef is browned, drain any excess fat and stir in the cheddar cheese soup, milk, ketchup, mustard, salt, and pepper.
Fold in the frozen hash browns gently until combined.
Transfer the mixture to a greased 9x13 inch baking dish and spread it evenly.
Sprinkle the shredded cheddar cheese on top, and then the diced pickles.
Bake in the preheated oven for 30-35 minutes until bubbly and the cheese is melted.
Remove from the oven and let it sit for 5-10 minutes before serving.
