Preheat the oven to 350° F.
Heat the olive oil in a medium saute pan. Add the onions, green pepper, carrots, celery, thyme, salt, and pepper.
Cook over medium-low heat, stirring occasionally, for 8 to 10 minutes, until the onions are translucent but not brown.
Remove from the heat and allow to cool slightly
Off the heat, add the Worcestershire sauce, stock, and tomato paste.
In a large bowl, combine the ground chuck, onion mixture, bread crumbs, and eggs, and mix lightly with a fork. (It's best to use a light hand when mixing, or your meatloaf will be dense)
Shape the mixture into a rectangular loaf pan and place it on a sheet pan covered with parchment paper.
Spread the ketchup evenly over the top.
Bake for 1 - 1 ¼ hours, until the internal temperature is 160 degrees F and the meatloaf is cooked through. (A pan of hot water in the oven, under the meatloaf, will keep the top from cracking.)
Let stand 10 minutes before serving
Serve hot.