Place sliced potatoes in a large pot, fill with water up to ⅔ full and bring to a boil. Cook potatoes for 6 minutes, then add onions and cook for an additional 2 minutes. Strain and set aside.
While potatoes are cooking, in a medium bowl combine soup, sour cream, 1 cup of cheese, ham, and seasonings. Mix until combined.
Layer half of the potato and onion mixture on the bottom of the pan and top with half of the soup mixture. Repeat the process with the remaining potatoes and soup mixture.
Sprinkle the remaining cheese on top.
Place in oven and bake uncovered for 40-45 minutes or until cheese is melted and bubbly.
Let sit for 5 minutes before serving.
Notes
Slice potatoes to a uniform width. Using a mandoline helps but be mindful that they are very sharp!
Refrigerate leftovers in a covered container for 3 to 4 days. Freeze portions in covered containers for up to 4 weeks.
Reheat in the microwave or covered with foil in the oven.