Preheat oven to 375 degrees.

Wash potatoes and cut into ¼″ thick slices (no need to peel unless you want to). Drop into boiling water for 3 minutes. During the last minute, add the sliced onions. Drain.

Meanwhile, in a bowl add the soup, milk,  and garlic powder. Whisk together until well combined.

Spread a little bit of the soup mixture in the bottom of a greased 11 x 7 inch baking dish. Layer half of the potatoes, half of the soup mixture, and half of the cheese. Repeat layers ending with cheese.

Bake at 375 degrees for 45-55 minutes or until hot and bubbly.