Rinse the corned beef under cold water to remove excess salt and pat it dry with paper towels.

Place the corned beef in a large pot or Dutch oven. Add enough water to cover the meat completely, then sprinkle the seasoning packet over the top. Bring the water to a boil, reduce the heat, cover, and let it simmer for 3 hours or until the beef is tender.

Preheat your oven to 375°F (190°C).

Combine the maple syrup, Dijon mustard, brown sugar, minced garlic, and black pepper in a small saucepan. Cook over medium heat, stirring occasionally, until the sugar is dissolved and the mixture thickens slightly, about 5 minutes. Set aside.

Once the corned beef is cooked, carefully remove it from the pot and place it in a baking dish. Discard the cooking liquid or save it to make a flavorful gravy.

Brush the maple mustard glaze generously over the entire surface of the corned beef.

Cover the baking dish with aluminum foil and bake for 20 minutes. Remove the foil and bake for an additional 10 minutes to let the glaze caramelize.

Remove the corned beef from the oven and let it rest for 10 minutes before slicing. Serve with your favorite sides like roasted vegetables or mashed potatoes.