Heat a large pan over medium heat. Add the oil and the onion, and cook for 5 or so minutes, until onion is cooked through.
Add the broccoli and cook for 5 more minutes, until bright green and tender.
While cooking the veggies, beat the eggs with the salt and pepper. Add to the pan and cook, stirring frequently, for 2-3 minutes, until eggs are cooked through. Remove from heat and allow to cool slightly.
In a clean pan, assemble quesadillas: on half of the tortilla, add ⅔ cup of egg mixture, topped with ⅓ cup cheddar cheese. Fold the tortilla over on itself and press firmly. Cook for 2-3 minutes per side until golden and crispy.
Remove from heat and cool completely on a wire rack.
Cut each quesadilla in half and stack each serving. Wrap tightly in plastic wrap, then place in a large ziplock bag. Keeps in the fridge for up to 3 days and in the freezer for up to 3 months.
Re-heating: Thaw overnight in the fridge (if frozen), or in 30 second increments in the microwave. Heat in a frying pan over medium heat 3-4 minutes per side, or in a George Foreman Grill for 2-3 minutes total.
