Layer sliced onions and peppers in bottom of 6-quart slow cooker.
Mix all seasoning ingredients in small bowl.
Arrange bratwurst over vegetables.
Sprinkle seasoning mix and brown sugar evenly over brats.
Add minced garlic.
Pour beer around edges (not directly over brats).
Cover and cook on LOW 6-8 hours or HIGH 3-4 hours.
Brats should reach internal temperature of 165°F.
Let rest 5 minutes before serving.
Serve on rolls with vegetables and preferred toppings.