Begin by gathering all necessary ingredients. Preheat your air fryer to 350 degrees F (175 degrees C).

To prepare the meatloaf, combine the breadcrumbs and milk in a medium-sized bowl and allow the mixture to rest for 5 minutes. Next, incorporate the ground beef, chopped onion, lightly beaten egg, fresh thyme, salt, and black pepper. Stir until all ingredients are well blended, taking care not to overmix.

While the breadcrumb mixture is soaking, shape the beef mixture into two rectangles, each approximately 3 x 4 1/2 inches.

For the glaze, mix together the ketchup, apple cider vinegar, light brown sugar, and Worcestershire sauce in a small bowl. Set aside for later use.

Generously spray the air fryer basket with cooking spray or line it with parchment paper to simplify cleanup. Place the meatloaf rectangles into the basket and spray the tops generously with cooking spray. Roast the meatloaf in the preheated air fryer for 20 to 25 minutes. After 18 minutes of cooking, brush the meatloaf evenly with the prepared ketchup mixture. The meatloaf is ready when it reaches an internal temperature of at least 155 degrees F (68 degrees C) as measured with an instant-read thermometer.

Carefully remove the meatloaf from the air fryer basket and allow it to rest for 5 minutes. Garnish with additional thyme leaves before serving. Enjoy your delicious air fryer meatloaf!