Set a skillet or griddle over medium-high heat and warm it for 2-3 minutes. If it gets excessively hot, lower the heat to medium.

Split the ground beef into 4 portions of about 4 oz each. Press one portion into a thin layer over half of a flour tortilla, keeping a 1/2-inch border. Season that portion with one-quarter of the salt, black pepper, and garlic powder.

Put the tortilla beef-side down in the heated skillet. Use a spatula to press the beef firmly against the cooking surface for 10-15 seconds, then leave it undisturbed for 2-3 minutes, until the beef edges are browned and crisp.

Turn the tortilla over so the cooked beef is facing upward. Scatter about 1/4 cup of shredded cheddar over the beef, then fold the tortilla in half and press it gently with the spatula.

Cook the folded quesadilla for 1-2 minutes per side, until the tortilla is golden and crisp and the cheese has melted completely. The ground beef should reach 160°F / 71°C.

Transfer the quesadilla from the skillet and allow it to rest for 30 seconds before cutting it into wedges. Repeat the process with the remaining beef and tortillas.

Serve the warm quesadillas with pickles and, if desired, diced onions, burger sauce, ketchup, or mustard.