Heat the olive oil in a medium saute pan. Add the onions, thyme, salt, and pepper and cook over mediumlow heat, stirring occasionally, for 8 to 10 minutes, until the onions are translucent but not brown.
Remove the pan from the heat, then add the Worcestershire sauce, chicken stock, and tomato paste. Allow to cool slightly.
In a large bowl, combine the ground chuck, onion mixture, bread crumbs, and eggs, and mix lightly with a fork. Don't mash or the meat loaf will be dense.
Shape the mixture into a rectangular loaf on a sheet pan covered with parchment paper.
Spread the ketchup evenly on top. Bake for 1 to 1 1/4 hours, until the internal temperature is 160 degrees F and the meat loaf is cooked through. Serve hot.
Notes
Place a pan of hot water in the oven on the rack under the meat loaf. This will keep the top from cracking.
Nutritional information is based on third-party calculations and should be considered estimates. Actual nutritional content may vary depending on the brands used, measuring methods, portion sizes, and other factors.