Prepare the Tortilla and Peppers:
If your tortillas are not pre-cooked, cook them first. Set aside.
Roast the poblano pepper by placing it on the top shelf of the oven under the broil setting. Leave the oven door slightly open. Roast until the skin is blistered and blackened, rotating as needed. This should take a couple of minutes per side.
Remove the roasted pepper from the oven and place it in a sealed bag or container to sweat. Once cool enough to handle, peel off the blistered skin and discard. Remove the stem and seeds, then slice the pepper.
Assemble the Quesadilla:
Heat a large nonstick skillet over medium heat. Ensure all ingredients are prepped and ready for quick assembly.
Add the butter to the skillet. Once melted, place the tortilla in the skillet.
Evenly spread the shredded cheese across the tortilla.
Lay the roasted poblano pepper slices in a single layer over the cheese.
Sprinkle garlic powder over the fillings and add cilantro if desired.
Cook the Quesadilla:
Once the cheese starts to melt, use a spatula to fold the tortilla in half, creating the quesadilla.
Cook for about 2 minutes, or until the tortilla is lightly browned. Flip and brown the other side for another 1-2 minutes.
Serve:
Remove the quesadilla from the skillet and let it rest on a cutting board for 1-2 minutes to allow the cheese to set.
Cut the quesadilla into triangles and serve with sour cream or your favorite sauces.