Preheat the oven to 375° F (190°C). Line a baking sheet with aluminum foil.

Warm 2 tablespoons of the olive oil in a frying pan over medium-high heat. Add the onion and sauté until translucent, about 4 minutes. Add the garlic and sauté until softened, about 1 minute longer. Stir in the Worcestershire sauce, remove from the heat, and let cool.

In a bowl, combine the beef, pork, the onion mixture, the bread crumbs, egg, 1 teaspoon salt, and ½ teaspoon pepper. Using your hands, mix until thoroughly combined. Divide the meat in half and, using your hands again, form two identical loaves, each about 10 inches (25 cm) long and 4 inches (10 cm) wide. Place the loaves on half of the baking sheet and spread the ketchup on top.

Pile the carrots and parsnips onto the baking sheet next to the meat loaves. Drizzle with the remaining 3 tablespoons olive oil and the rosemary, season well with salt and pepper, and toss to coat. Spread the carrots and parsnips into a single layer. Bake, stirring the vegetables once about halfway through, until the vegetables are caramelized on the edges and fork-tender and an instant-read thermometer inserted into the meat loaves reaches 145° F (63°C), about 45 minutes. Remove the baking sheet from the oven and transfer the meat loaves to a cutting board. Cut the meat loaves into thick slices and serve with the vegetables.