Creamy and Comforting Mushroom Soup

Ingredients

• 40 g unsalted butter
• 1 large onion, peeled and chopped
• 1 stick celery, finely chopped
• 1 bay leaf
• 1 clove garlic, peeled and crushed
• 500 g mushrooms
• 1 tsp salt
• 1 tbsp plain flour
• 1 litre hot chicken or vegetable stock
• 100 ml milk or single cream
• 2 tbsp chopped parsley
• single cream or creme fraiche to serve
• squeeze of lemon juice