Lightly rub one side of a large, burrito-sized tortilla with olive oil (1 tsp). Place the tortilla, oiled side down, into a preheated nonstick skillet over medium-low heat. Spread 3/4 cups of cheese onto the tortilla, leaving about 1/2" of space between the cheese and the edge of the tortilla. Add the meat mixture and sprinkle with the onions. Top with the remaining cheese and the other tortilla. Lightly oil the top tortilla and lid the skillet. Let cook for 1–2 minutes, or until the bottom tortilla is golden-brown. CAREFULLY flip the quesadilla and continue cooking (lid the skillet again) until golden-brown on the second side, an additional 2–3 minutes.

Carefully transfer the quesadilla onto a cutting board and cut into slices as you would a pizza.

Divide the cheese into 2 piles with 3/4 cups each. For each tortilla, spread half of one cheese pile onto half of each tortilla, leaving about 1/2" between the cheese and the edge of the tortilla (see the photo here: these are not the same quesadillas, but you can see how I've arranged the filling). Add half of the meat mixture to the same half of each tortilla and sprinkle each with half of the onions. Now, for each tortilla, spread the remaining cheese in each pile over the top of the filling. Fold the other half of the tortilla over the filling. Rub 1/4 tsp of olive oil onto the top of each quesadilla. Place the quesadillas, oiled-side down, into a preheated non-stick skillet over medium-low heat. Rub 1/4 tsp olive oil onto the exposed side of each quesadilla. Lid the skillet. Let cook for 2–3 minutes, or until the bottom tortilla is golden-brown. Carefully flip the quesadillas and continue cooking (lid the skillet again) until golden-brown on the second side, an additional 2–3 minutes.

Carefully transfer the quesadillas onto a cutting board and cut each quesadilla into 3 roughly equal slices.