Heat the olive oil in a large skillet over medium- high heat. Add the onion and poblano and cook until softened, about 4-5 minutes.
Push the veggies to one side of the pan and add the ground beef. Brown one side before breaking apart, mixing with the veggies, and fully cooking.
Once the beef is fully cooked, add the taco seasoning, corn, and black beans (undrained). Cook for 2-3 minutes until the mixture begins to thicken and reduce to a simmer for another 3-4 minutes while you grate the cheese.
Transfer the quesadillas filling to a bowl and carefully wipe the skillet clean. You can also use a separate griddle to cook more quesadillas at one time.
Use cooking spray or a light drizzle of oil to coat the skillet before adding tortillas. Add 3/4 oz of cheese to one half of a tortilla, followed by 2 1/2 oz of the filling and another 3/4 oz of cheese on top. Fold to close and cook both sides until golden brown, about 1-2 minutes per side.