If you can't find Russet potatoes in your area, both Idaho potatoes (actually a Russet) and Yukon Gold potatoes are nice starchy varieties that should work well in this recipe. Yukon gold is less starchy than a Russet, but still considered a starchy potato. It has golden or yellow flesh. And, like it's Russet cousin, it's great for baking, mashing and frying. It's a good option in this easy ground beef casserole recipe.