Preheat your oven to 350 degrees F and line a baking sheet with parchment paper.
In a small bowl, combine the gluten free breadcrumbs and milk. Let them soak for 5 minutes until the crumbs are soft and mushy.
In a large bowl, combine the ground beef, soaked breadcrumbs, eggs, diced onion, garlic, worcestershire sauce, dijon mustard, salt, pepper, and thyme. Mix gently with your hands until everything is just combined. Do not overmix.
Shape the mixture into a loaf about 9 inches long and 5 inches wide on the prepared baking sheet. Smooth the top and sides with your hands.
In a small bowl, whisk together the ketchup, brown sugar, and apple cider vinegar until smooth. Brush half of the glaze evenly over the top and sides of the meatloaf.
Bake for 40 minutes, then remove from the oven and brush the remaining glaze over the top. Return to the oven and bake for another 15 to 20 minutes until the internal temperature reaches 160 degrees F and the glaze is caramelized.
Let the meatloaf rest for 10 minutes before slicing. Serve with mashed potatoes and your favorite gluten free sides.