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