Mushroom and potato soup

• 500 grams mushrooms whole
• 200 grams potatoes coarsely chopped or chats potatoes
• 1 large onion sliced
• 3 cloves garlic crushed
• 1 litre vegetable stock
• 1 litre milk or soya milk or light milk or rice milk
• ½ bunch or ¼ cup fresh basil leaves chopped ( or 1 tablespoon dried basil leaves)