To caramelize the onions. Heat the oil and butter in a large heavy bottomed Dutch oven or saucepan over low heat. Add onions. Cook onions stirring regularly until onions are dark golden brown color, about 45 minutes
Increase heat to medium. Add rosemary and flour. Stir and cook for 2 to 3 minutes. Gradually stir in red wine. Let reduce for 5 to 10 minutes then add beef stock and simmer for 20 minutes. Finish with fresh ground pepper.
Brush slices with olive oil and toast under broiler until lightly golden. Rub with garlic.
Ladle soup into ovenproof bowls. Top each with toasted bread and provolone cheese. Broil until cheese melts and bubbles, about 2 to 3 minutes. Garnish with chopped chives
