Over medium-low heat, heat ham in a nonstick frying pan sprayed with nontick spray. While ham is warming, whisk together the egg and egg substitute. Add to ham and stir until eggs are just barely cooked. Salt and pepper to taste.
Place one tortilla in another frying pan, over medium heat. Sprinkle with half of the cheddar and half the ham and egg mixture. Top with half of the mozzarella. Place second tortilla on top.
Gently lift the tortilla to see when it is lightly browned. When it is, slide quesadilla onto a plate. Place pan on top of plate and flip so that the uncooked side is now on the bottom. Cook until lightly browned. Slide onto a cutting board and cut into 6 slices.