Never tried cooking brats like this before, but wow, what a game-changer!

1. Preheat oven to 350°F (175°C).
2. In a large Dutch oven or oven-safe pan, melt butter and olive oil over medium heat.
3. Add sliced onions and sauté until tender and browned (about 20-25 minutes).
4. Add chopped garlic and sauté for 2-3 minutes until fragrant.
5. Arrange sausages in the pan on top of the onions.
6. Pour beer and beef stock into the pan, ensuring sausages are almost covered.
7. Stir in Dijon mustard, salt, and pepper.
8. Bring mixture to a simmer on the stovetop, then transfer to the preheated oven.
9. Bake uncovered for 30-40 minutes, or until sausages are cooked through.
10. Garnish with chopped parsley, if desired.

Enjoy!