Creating your Sheet Pan Meatloaf and Veggies is straightforward. Follow these steps to make a delightful meal:

1. Preheat Oven: Preheat your oven to 350°F (175°C).
2. Prepare the Meatloaf Mixture: In a large bowl, mix together the ground beef, breadcrumbs, egg, chopped onion, minced garlic, Worcestershire sauce, ketchup, salt, pepper, Italian seasoning, and milk until well combined.
3. Form the Meatloaf: Shape the meat mixture into a loaf and place it in the center of a large, greased sheet pan or baking tray.
4. Chop the Vegetables: While the meatloaf is resting, chop your chosen mixed vegetables into even bite-sized pieces.
5. Season the Veggies: In a bowl, toss the vegetables with olive oil, salt, pepper, and thyme if using. Mix well to coat evenly.
6. Add to the Pan: Arrange the seasoned vegetables around the meatloaf on the sheet pan.
7. Top the Meatloaf: Spread a thin layer of ketchup over the top of the meatloaf for added flavor and a nice glaze.
8. Bake in the Oven: Place the sheet pan in the preheated oven and bake for about 45 minutes, or until the meatloaf is cooked through (internal temperature of 160°F or 70°C).
9. Check for Doneness: After 40 minutes, check the meatloaf with a meat thermometer to ensure that it has reached a safe internal temperature.
10. Rest the Meatloaf: Once done, remove the pan from the oven and let it rest for about 10 minutes before slicing. This allows the juices to redistribute.

These steps will guide you in creating a complete meal that is both incredibly delicious and easy to prepare!