Preheat your oven to 375°F and line a baking sheet with parchment paper or lightly oil it. While the oven heats, dice your onions, celery, and carrot into uniform 1/4-inch pieces—this ensures even cooking and a consistent texture throughout the meatloaf. Mince your garlic and set all vegetables aside in a small bowl. Make sure your egg and cooked quinoa are at room temperature, as this helps them integrate better with the meat mixture.

Heat your high-heat oil in a large skillet over medium-high heat until shimmering. Add the diced onions, celery, carrot, and garlic, stirring occasionally, and cook for 5 to 7 minutes until the vegetables are softened and the onions become translucent. This caramelizes the vegetables slightly and builds a deeper flavor foundation. Reduce heat to medium, then add the dried thyme, oregano, and fennel seeds, stirring constantly for 1 to 2 minutes to bloom the spices and release their essential oils. Remove the pan from heat and let the vegetable mixture cool to room temperature—this prevents the egg from cooking prematurely when mixed with the meat.

In a large bowl, combine the cooled sautéed vegetables from Step 2 with the ground beef, cooked quinoa, room-temperature egg, Worcestershire sauce, salt, and black pepper. I like to use my hands to gently mix everything together—work just until the ingredients are evenly distributed, being careful not to overwork the mixture, as this can make the meatloaf dense and tough. The quinoa adds moisture, fiber, and a slight nutty flavor that balances the beef beautifully.

Transfer the meatloaf mixture onto your prepared baking sheet and shape it into a loaf form roughly 9 inches long and 5 inches wide, using your hands or a spatula. Try to form it evenly so it cooks uniformly. Place it in the preheated 375°F oven and roast for 30 minutes—this initial cooking allows the meatloaf to set and the flavors to meld.

While the meatloaf is roasting, whisk together the ketchup and brown sugar in a small bowl to create a simple glaze. After the initial 30 minutes of roasting, remove the meatloaf from the oven and spread the ketchup-brown sugar mixture evenly over the top. Return it to the oven and continue roasting for another 30 to 45 minutes, until a meat thermometer inserted into the thickest part reads 165°F. The glaze will caramelize and create a delicious crust while the browning sugar adds subtle sweetness that complements the savory beef and spices.

Remove the meatloaf from the oven and let it rest on the baking sheet for 10 minutes before slicing. This resting period allows the juices to redistribute throughout the meat, ensuring each slice stays moist and tender. Slice and serve warm with your choice of sides.