In your 6-quart slow cooker, combine 4 cups of chicken stock, 2 cups chopped sweet onion, ½ cup each of chopped carrot, celery, and red bell pepper, along with ¼ cup unsalted butter, 1 ½ teaspoons kosher salt, ½ teaspoon black pepper, and ¼ teaspoon crushed red pepper. Cover and cook on HIGH for about 3 hours, or until the vegetables are tender and aromatic.

Once the vegetables are tender, whisk in 12 ounces of shredded sharp Cheddar cheese, 8 ounces of cream cheese, and 1 cup of milk. Cover again and continue cooking on HIGH for 30 minutes, stirring occasionally.

Whisk together ¼ cup cornstarch with the remaining ¼ cup of milk in a bowl until smooth. Add this mixture to your slow cooker, cover, and cook on HIGH for another 15 minutes.

Slice off the tops of 8 soft pretzel buns and scoop out the centers, leaving thick shells for holding your soup.

Ladle the creamy slow-cooker cheddar soup into the hollowed-out pretzel bun bottoms. Top each bowl with crumbled cooked bacon and sliced scallions. Serve the tops of the pretzel buns on the side.