Preheat the oven to 350 degrees F (175 degrees C).

Bring a large pot of salted water to a boil. Add the potatoes and cook until tender but still firm, about 15 minutes. Drain and let cool.

While the potatoes are cooking, place the eggs in a saucepan and cover with cold water. Bring the water to a boil, then immediately remove it from heat. Cover and let the eggs sit in the hot water for 10 to 12 minutes.

Remove the eggs from hot water and place them under cold running water to cool.

Slice the cooled potatoes into rounds and peel the cooled eggs, slicing them as well.

Layer the ingredients: Starting and ending with potatoes, layer the sliced potatoes and eggs in the 9×13-inch casserole dish. Make sure to sprinkle each layer of eggs with seasoning salt.

In a small saucepan, cook and stir the sour cream and margarine over low heat until melted.

Pour the melted mixture over the casserole and sprinkle lightly with seasoning salt.

Bake in the preheated oven for 30 minutes.