Make this recipe a recipe that people in that category can eat. categories: ['low_calorie'], recipe: melt butter in a large saucepan over medium heat. add onions and sea salt and cook, stirring occasionally, for 30 minutes or until onions are deep golden. add cider and simmer until reduced by half, then add stock and simmer for 10 minutes. season with pepper. meanwhile, place bread on a foil-lined tray and cook both sides under a hot grill until dried but not browned. spread with mustard and top with cheese, then grill until cheese bubbles and browns. serve soup topped with the croûtons and sprigs of thyme.

Target recipe: in a large skillet, sauté onions in butter until crisp-tender. transfer to an ungreased 5-quart slow cooker/crock pot. add the broth, worcestershire sauce, and bay leaves. cover and cook on low for 5 to 7 hours or until the onions are tender. discard bay leaves. top each serving with french bread and cheeses.