I start by heating my griddle or skillet over medium-low heat. If it isn't non-stick, I give it a light spray of non-stick cooking spray first. I personally like using a cast-iron griddle because it holds heat evenly, which helps the brie melt without scorching the tortilla underneath.
I lay two tortillas flat on the warm skillet and arrange half of the brie slices over each one. Then I scatter the chopped tomatoes, avocado, parsley, and scallions on top, along with a dash of hot sauce and a light pinch of salt and pepper. I try not to overload either tortilla so it stays easy to flip
I let the tortillas cook for about 2 minutes over low heat, gently loosening them from the skillet with a spatula so they don't stick. This step also lets the bottom tortilla turn slightly golden while the brie starts to soften from the heat below.
Once the bottom is set, I place another tortilla on top of each one to close the quesadilla. Using a wide spatula, I carefully flip each quesadilla over and let it cook for another 2 to 4 minutes, or until the brie is fully melted and gooey in the center.
I remove the quesadillas from the skillet and cut each one into quarters using a sharp knife or pizza cutter. A quick sprinkle of chopped scallions on top finishes it off nicely, and I like to serve them while they're still hot and the cheese is stretchy.