Preheat the oven to 350 degrees. Prepare your baking pan.
Prepare a 9×13 baking dish or sheet pan by covering with parchment paper or aluminum foil sprayed with non-stick cooking spray. I recommend using a wire rack to set the meatloaf on so the grease drops under the meatloaf during the cooking process. If you have a loaf pan, spray it with non-stick cooking spray.
Add all of the meatloaf ingredients to a large bowl and mix together. You can mix with a wooden spoon or wet hands. I prefer to wear kitchen gloves that I spray with non-stick spray and then mix by hand.
Once you have all of the ingredients mixed well, shape the beef mixture into a loaf on you prepared baking dish or press into your prepared loaf pan.
Place the pan of meatloaf on the middle rack in your preheated oven. Bake for 1 hour to 1 hour 15 minutes. Your meat thermometer should read 160° when inserted into the center of the meatloaf.
In a small bowl, stir together the ketchup, mustard and brown sugar, if using. Set aside to glaze the meatloaf after it is done baking.
Remove the meatloaf from the oven once the internal temperature reaches 160°. Spread the meatloaf glaze over the top generously, allowing some to drip down the sides. Then return the baking dish to the oven. Allow the glaze to bake onto the meatloaf for about 10-15 minutes.
Remove the meatloaf from the oven and allow it to rest for about 10 minutes before serving. Allowing the meatloaf to rest lets the juices stay in the meat for a more moist and flavorful meal. Slice, serve and enjoy.