Set up your salad, so it will be ready to go when the quesadillas are hot and ready to serve. Wash and dry the lettuce and tear in pieces. In a cup, whisk the garlic, lime, olive oil, chipotle powder and salt, and reserve.
In a large skillet over medium-high heat, heat the second measure of olive oil and add the onion and red bell pepper. Sauté, stirring, until the vegetables are soft. Add the chicken breast and sauté, stirring, until the meat is cooked through and golden. Add the jalapeno and stir for a minute, then take off the heat and scrape into a bowl. Let cool to room temperature, then add the scallions and cheese and toss to mix.
Preheat the oven to 200°F to hold the finished quesadillas.
On a large cutting board, lay out four tortillas and distribute the filling between them, covering each evenly. Top with another tortilla and press lightly. At this point you can carefully stack them.
Heat a large skillet over high heat. When hot, place a quesadilla in the pan and cook for a couple of minutes, peek under to see if it looks browned and toasty. When the cheese is melting, press with a spatula to hold the quesadilla together, then carefully flip. The second side will only take a minute or two, then slide out onto the cutting board and slice into wedges. Move to a heat safe platter and slide in the oven until the rest of the quesadillas are done.
To serve, divide the salad between four dinner plates and drizzle with dressing, toss to coat. Serve the hot quesadillas on top of the salad, with bottled salsa spooned over.