1. Heat a large nonstick skillet over medium-high heat. Add the oil, then add the egg whites. Swirl the pan to spread the egg whites into a round that covers the bottom. Cook until the whites are set, then slide onto a cutting board.
2. When the egg white has cooled slightly, spread with the pesto. Arrange the spinach leaves, then ham slices on top in a single layer, then roll into a cylinder. Cut into eight 1-inch spirals and serve.
Tip: The rolls also taste good cold and can be refrigerated in an airtight container for up to 1 day.