Wash potatoes. Leaving skins on, grate potatoes. Rinse grated potatoes in a colander with cold water. Dry thoroughly.
Combine potatoes and oil. Cook potatoes in a large non-stick skillet over medium high heat until lightly browned. Cool slightly.
Coat a 13 x 9 baking sheet with nonstick spray. Combine potatoes and cheese. Spread evenly on baking sheet.
Place in a preheated 375°F oven for 20 minutes or until hash browns are golden brown and crisp. Remove from oven and top with additional cheese if desired.
Cut into 24 squares and serve with 1 ounce dollop of salsa.