Preheat your oven to 350°F (175°C). Rinse the corned beef brisket under cold water to remove excess brine, then pat dry with paper towels.

In your Dutch oven, layer the chopped onions and smashed garlic cloves at the bottom, followed by two bay leaves. Place the corned beef brisket fat-side up on top of these aromatics. Pour in the dark beer or beef broth around the sides, ensuring the liquid covers the base.

Cover the Dutch oven tightly with its lid and place it in the preheated oven. Bake for exactly 1 hour. After the hour is up, reduce the oven temperature to 300°F (150°C) and allow the corned beef to continue cooking for an additional 2 hours.

Carefully remove the Dutch oven and uncover it. Add the peeled and chopped carrots, along with the halved baby potatoes. Cover the pot again and return it to the oven for 1 hour.

With just 30 minutes left, stir in the cabbage wedges evenly around the beef and veggies. Cover again to steam the cabbage.

Check the corned beef for doneness; it should be fork-tender and reach an internal temperature of 145°F to 160°F (63°C to 71°C). If not tender, cover and cook a bit longer.

Slice the rested corned beef against the grain and serve warm with carrots, potatoes, and cabbage.