In a large skillet, heat the olive oil. Once hot, add the spinach leaves and artichoke hearts. When the spinach is wilted remove the mixture from the pan and set aside.
Add the egg whites and scramble until cooked through. Add 1/2 of the egg whites to the bottom of each roll or English Muffin, spoon the spinach and artichoke mixture on top, add 1/2 cheese slice, return to the skillet, and cover to melt the cheese, about 30 seconds. Add the other half of the bread.