Preheat your oven to 350°F (175°C).
2. Caramelize Onions and Apples
In a large oven-safe skillet or Dutch oven, heat olive oil and butter over medium heat.
Add onions and apples and cook, stirring occasionally, until soft and golden brown, about 20–25 minutes.
Stir in minced garlic and cook until fragrant.
3. Add Bratwursts
Nestle the bratwursts among the onions and apples.
4. Add Liquid and Seasoning
Pour in beer and beef broth, ensuring the brats are mostly covered.
Stir in Dijon mustard, and season with salt and pepper.
5. Bake
Bring to a simmer on the stove, then transfer to the oven.
Bake uncovered for 30–40 minutes until the brats are cooked through and have absorbed the flavors.
