Preheat oven to 325 degrees F and line a baking sheet with foil, then a piece of parchment on top. In a medium saute pan heat the olive oil over medium-low heat. Add the onions, garlic, thyme, kosher salt, and pepper, stirring occasionally until onions are soft, about 10 minutes.
Remove from heat and stir in Worcestershire sauce, tomato paste, and beef stock; let cool. In a large bowl, combine the ground beef, panko, eggs, and the onion-garlic mixture. Stir it together with a fork gently, just to combine.
On top of the parchment paper, shape meatloaf mixture into a rectangular loaf size. Spread the ketchup smoothly over the top. Bake until internal temperature is 160 degrees F, about 1 hour to 1 hour 10 minutes. Remove from oven and let rest for 10-15 minutes before slicing. Serve warm.