Preheat oven to 350F degrees.
Cook 1 pound ground beef in a skillet over medium heat until no longer pink, breaking it up as it cooks.
Drain fat using a colander and place cooked meat into a 9x13-inch baking dish.
In a small bowl, combine 1/4 cup dill pickle relish, 3 Tablespoons ketchup, 3 Tablespoons mustard, 4 cloves garlic, minced, and 1 can cream of mushroom soup. Mix well.
Pour sauce mixture over the ground beef in the baking dish.
Sprinkle 1 cup shredded cheddar cheese evenly over the sauce.
Cover the top of the casserole with 1 bag frozen french fries in an even layer.
Bake for 40 minutes until fries are golden and crispy.
Remove from oven and let rest for 5 minutes before serving.