1. Prepare Sauerkraut Topping Mixture:

• Ensure your sauerkraut is thoroughly rinsed under cold water and then squeezed very well to remove as much excess liquid as possible. This is key to preventing a watery result.
• Peel, core, and finely chop the apples. Cook and crumble the bacon (if not using pre-crumbled). Finely chop the onion.
• In a large mixing bowl, combine the rinsed and well-drained sauerkraut, finely chopped apples, crumbled cooked bacon, packed brown sugar, finely chopped onion, and ground mustard.
• Stir these ingredients together until everything is well combined.

2. Layer Brats and Topping in Slow Cooker:

• Lightly grease the insert of your 5-quart slow cooker if desired (though often not strictly necessary if brats have some fat).
• Place the uncooked bratwurst links in the bottom of the slow cooker. You can arrange them in a single layer if possible, or overlap slightly if needed. (Optional: Season brats lightly with salt and pepper here, being mindful of salt in bacon/sauerkraut).
• Spoon the prepared sauerkraut, apple, and bacon mixture evenly over the top of the bratwurst in the slow cooker.

3. Slow Cook:

• Cover the slow cooker securely with its lid.
• Cook on the LOW setting until a thermometer inserted into the center of a sausage reads 160°F (71°C) and the brats are cooked through and tender. This typically takes 6-8 hours.

4. Serve:

• Once cooked, the brats will be tender and the topping fragrant and softened.
• To serve, split the brat buns. Place one cooked bratwurst link into each bun.
• Using a slotted spoon (to drain off excess liquid from the slow cooker), generously top each brat with the warm sauerkraut, apple, and bacon mixture from the slow cooker.
• Sprinkle with thinly sliced green onions, if desired.
• Serve immediately and enjoy your delicious Slow Cooker Brats and Sauerkraut!