Preheat the oven to 325°
On the stovetop over medium-high heat melt 1 tablespoon of butter in the bottom of your dutch oven and sautee the chopped onions for 2 to 3 minutes then remove from heat.
Cut carrots and celery into large chunks about 1 inch in size and add to the dutch oven. Peel and cut potatoes in half (or quarter them if they are very large) and add them to the dutch oven as well. Give the vegetables a toss so that they are evenly distributed.
In a small bowl mix ketchup, onion powder, dried chopped onion and garlic powder and mix well.
Remove the corned beef from the packaging and rinse it. Cover the top (the fatty side) of the with the ketchup mixture and place in the dutch oven right ontop of the root vegetables.
Core your cabbage and cut into large pieces. Pack all the area around the corned beef with the cabbage. Pour in the beef broth, cover and cook it in the oven for 3 hours.
After it is done cooking remove the corned beef from the pot and slice it to serve.
