My mom’s soup that I remember from childhood. Probably as basic as it gets. Add cheese of choice and croutons, if desired.
Melt butter in a skillet over medium heat. Cook and stir onions in melted butter until clear and browned, 10 to 15 minutes; transfer to a slow cooker. Add beef broth, garlic, salt, and black pepper to the slow cooker.
Cook on High for 4 hours or on Low for 8 hours.
Per Serving: 120 calories; protein 3.1g; carbohydrates 9.6g; fat 8.1g; cholesterol 20.3mg; sodium 584.5mg.