Heat a non-stick pan over medium heat. Cook sausage or bacon until browned and cooked through, then transfer to a plate. If using cooked ham, you can heat it up or simply add it over the cheese in step 4. Wipe any excess oil from the skillet if necessary. Reduce the heat to low.
In a measuring cup, add 2 eggs with a pinch of salt and pepper, or season to taste. Beat the eggs with a fork. Pour the beaten eggs into the pan and swirl to spread them evenly over the bottom. Cook over low heat until the eggs are nearly cooked through (tilting the pan should not make them run).
Sprinkle the top with 2 tablespoons of shredded cheese, then cover with a tortilla. The cheese will make the tortilla adhere to the egg. Use a large spatula to slide under the egg and quickly flip it over.
Sprinkle another 2 tablespoons of cheese or add cheese to your liking. Sprinkle your cooked protein (sausage, bacon, or ham) over half of the surface and fold the tortilla in half. Sauté on both sides until golden brown.*
Remove from the skillet and use a pizza cutter to cut the quesadilla into wedges. Serve warm.