English onion soup with sage & cheddar

INGREDIENTS

• 1 good knob butter
• olive oil
• 1 good handful fresh sage leaves, 8 leaves reserved for serving
• 6 cloves garlic, peeled and crushed
• 5 red onions, peeled and sliced
• 3 large white onions, peeled and sliced
• 3 banana shallots, peeled and sliced
• 300 g leeks, trimmed, washed and sliced
• sea salt
• freshly ground black pepper
• 2 litres organic beef, vegetable or chicken stock, hot
• 8 slices good-quality stale bread, 2cm thick
• 200 g Cheddar cheese, freshly grated
• Worcestershire sauce