Preheat the oven to 350 degrees F. Line a sheet pan with parchment paper.
Heat 1 tablespoon of olive oil in a medium (10-inch) saute pan. Add the onions, thyme, 2 teaspoons salt, and 1 teaspoon pepper and cook over medium-low heat, stirring occasionally, for 8 to 10 minutes, until tender but not browned. Off the heat add the Worcestershire sauce, chicken stock, and tomato paste. Cool slightly.
In a large bowl combine the ground meats, the onion mixture, breadcrumbs, and eggs and mix lightly with a fork. (Don't mash the mixture or the meatloaf will be too dense.) Divide the mixture into six (10-ounce) portions and place them on the prepared sheet pan.
Squeeze ketchup in a zigzag pattern on top of each meatloaf. Bake for 45 minutes to 1 hour, until the internal temperature is 155 to 160 degrees. Serve hot with a garnish of thyme.