Preheat the oven to 350°F (175°C). Gather all ingredients. Line an 8x4-inch loaf pan with a double layer of aluminum foil, ensuring a 3-inch overhang on both long sides for easy removal. Lightly coat with cooking spray and place the pan on a baking sheet.

In a large mixing bowl, combine the ground beef, stuffing mix, water, egg, kosher salt, poultry seasoning, and 1/2 cup of the ketchup. Using your hands, mix until evenly combined, being careful not to overwork the mixture.

Press the mixture evenly into the prepared loaf pan and place it on the baking sheet.

Bake in the preheated oven until the top is golden and the sides are bubbling, approximately 35 minutes.

While the meatloaf bakes, prepare the topping by mixing the remaining 1/2 cup ketchup with the light brown sugar in a small bowl until smooth.

Remove the meatloaf from the oven and spread the ketchup-brown sugar mixture evenly across the top.

Return the meatloaf to the oven and bake at 350°F (175°C) for an additional 10 to 15 minutes, or until an instant-read thermometer inserted into the center registers 160°F (71°C). Allow the meatloaf to rest for 5 minutes after baking.

Using the aluminum foil overhang as handles, carefully lift the meatloaf from the pan and transfer it to a cutting board. Slice into 8 portions and serve.