Preheating the Oven: Begin by setting your oven to preheat at a temperature of 325°F (163°C) to ensure it is adequately warmed for baking.
Combining Ingredients: In a large baking dish, measuring 9x13 inches, combine the prepared potatoes, grated cheddar cheese, crumbled bacon, and sliced green onions. Evenly sprinkle the garlic salt across the mixture to season.
Adding Mayonnaise: Introduce the mayonnaise to the dish, carefully folding it in to coat all ingredients uniformly. This will ensure each element melds together during the baking process, enhancing both flavor and texture.
Baking the Dish: Transfer the baking dish to the preheated oven. Allow the mixture to bake for approximately 1 hour and 30 minutes. The dish should be removed from the oven once the potatoes have softened and the surface has achieved a golden-brown hue.