Mushroom, spinach, kale and sweet potato pie Serves: 4 Ingredients 2 tbsp olive oil 500g closed cup mushrooms, thickly sliced 2 cloves garlic, crushed 250ml vegetable stock 300g cooked sweet potatoes, cut into chunks 2 tbsp light crème fraîche 250g spinach, wilted 100g kale, cooked 150g feta cheese, cubed salt and freshly ground black pepper