01 -
Cook chopped onions in a skillet over medium-low heat until translucent and fragrant, about 5 minutes.
02 -
In a large bowl, mix ground beef, sautéed onions, milk, bread crumbs, egg, salt, and pepper until just combined. Avoid overmixing to maintain tender texture. Transfer to a lightly greased 9x5-inch loaf pan and shape evenly.
03 -
In a small bowl, whisk together ketchup, brown sugar, and prepared mustard until smooth. Spread glaze evenly over the top of the meat mixture.
04 -
Bake in a preheated oven at 350°F for about 60 minutes, or until the internal temperature reaches 160°F measured with an instant-read thermometer.
05 -
Allow meatloaf to rest for 5-10 minutes before slicing to retain juices. Serve warm with preferred sides.