Preheat oven to 425°F.
In a large bowl, toss potato slices with chili powder, cumin, chipotle powder (if using), and oil. Spread on the baking sheet, with as little overlapping as possible.
Bake until tender on the inside and slightly crispy on the outside, about 25 minutes. For crisper potatoes, cook for 5–10 more minutes, or until potatoes reach desired texture.
About 5 minutes before potatoes are done, combine egg whites, eggs, salt, and pepper in a medium-large bowl. Add 1 tablespoon water, and thoroughly whisk. Bring a skillet sprayed with nonstick spray to medium heat. Cook and scramble until set, about 3 minutes.
Arrange cooked potato slices on a serving dish. Top with spinach and scrambled eggs. Sprinkle with cheese, and top with salsa. Serve immediately.