Preheat oven to 350°F (175°C).
In a large bowl, combine ground beef, breadcrumbs, milk, egg, onion, garlic, Worcestershire sauce, thyme, salt, and pepper. Mix until just combined.
Form the meat mixture into a loaf shape and place in a 9x5 inch loaf pan.
In a small bowl, whisk together ketchup, brown sugar, and Dijon mustard. Spread half of the glaze over the top of the meatloaf.
Bake the meatloaf for 45 minutes. Apply the remaining glaze and bake for another 15 minutes or until the internal temperature reaches 160°F (71°C).
While meatloaf bakes, place cubed potatoes in a pot of salted water. Bring to a boil and simmer for 15-20 minutes until fork-tender.
Drain potatoes and mash with 4 tbsp butter and heavy cream until smooth. Season with salt and pepper.
In a separate saucepan over medium heat, melt 1 tbsp butter. Add corn kernels and cook for 5 minutes until heated through. Season with salt and pepper.
Rest the meatloaf for 10 minutes before slicing. Serve with mashed potatoes and buttered corn.