Herby sausage, apple & sourdough stuffing

Ingredients

• 1 sourdough loaf (350-400g) -
• 1 tbsp olive oil, plus extra for frying and drizzling -
• 150ml chicken stock -
• 50g unsalted butter -
• 1 large leek, halved through the centre, washed and sliced -
• 1 onion, finely chopped -
• 2 tsp fennel seeds -
• 6-8 sausages (400g) -
• 2 apples, peeled and chopped -
• small bunch of rosemary, leaves picked and finely chopped -
• 4 sage leaves, finely chopped plus 4 whole leaves to serve -
• 1 large egg -