I love mushroom risotto and I love leeks and cashews however the only risotto recipe I had with these ingredients was with brown rice, boiled in a pot. I prefer the traditional method of cooking risotto and with arborio rice so I used that recipe as a guide, along with another mushroom risotto recipe I had and it is delicious. (Believe it or not, the first time I cooked this recipe I forgot to add the cashews - after all that! Anyway, it still tasted great even without the cashews, but is better with them.)
Use the best quality stock you can as with any risotto, the quality of stock makes a huge difference. Preferably, make your own using one of the many chicken stock recipes on 'Zaar as a guide. (It should be a criminal offence to throw away a chicken carcass I reckon!) Alternatively, Campbell's "Real Stock" from the shop is very good.