01 -
Bring a large pot of salted water to a boil. Cook elbow macaroni according to package instructions until al dente. Drain thoroughly and set aside.
02 -
Melt 2 tablespoons unsalted butter in a medium saucepan over medium heat. Whisk in the all-purpose flour and cook for 1 minute, stirring constantly.
03 -
Gradually whisk in the whole milk, stirring constantly until smooth. Cook for 2 to 3 minutes until the sauce thickens.
04 -
Lower heat to low. Stir in shredded cheddar cheese, mozzarella cheese, mustard powder, garlic powder, salt, and black pepper. Stir until all cheese is melted and the sauce is smooth.
05 -
Gently fold the cooked macaroni into the cheese sauce until evenly coated. Remove the saucepan from heat.
06 -
Lay four flour tortillas on a work surface. Evenly divide approximately 1/2 cup of the macaroni and cheese mixture across each tortilla, leaving a 1/2-inch border at the edges.
07 -
Place a second tortilla over the macaroni and cheese filling to create a sandwich for each quesadilla.
08 -
Heat a large skillet or griddle over medium heat. Melt a portion of the remaining butter. Carefully transfer an assembled quesadilla to the skillet. Cook for 2 to 3 minutes per side, pressing gently with a spatula, until golden and crisp. Repeat with each quesadilla, adding more butter as needed.
09 -
Transfer cooked quesadillas to a cutting board. Let rest for 1 to 2 minutes, then cut into wedges. Serve immediately.