Preheat your oven to 180°C (350°F) and grease a 9×13-inch baking dish.

Peel and dice potatoes into 1-inch cubes and place them in a large mixing bowl.

Cook bacon in a skillet over medium heat until crispy, then crumble it into pieces.

In the bowl with potatoes, add ¾ of the cheddar cheese, crumbled bacon, garlic powder, and salt; mix gently.

Stir in the mayonnaise until potatoes are fully coated, being careful not to over-mix.

Transfer the mixture into the baking dish, level it off, and sprinkle remaining cheddar on top.

Bake in the oven for about 90 minutes or until the potatoes are tender and the top is golden.

Remove from oven, let cool slightly, and garnish with sliced green onions before serving.