This came out quite well. I got compliments and was asked for the recipe. I think 2 leeks, as called for in the recipe, is not enough. Of course, with leeks, even "large" leeks, you never know exactly how much useable leek you will get. I will use more leeks next time. I used fresh thyme, which means spending some time (yeah, I know) stripping the little leaves off. If you're in a hurry use dried. Otherwise, I used the slicing disk of a food processor for the sweet potatoes and a mandoline for the potatoes (prettier that way). So that part was pretty quick.
Re the instructions; Why use cooking spray on the pie pan when you are going to use parchment paper or foil to line the bottom? OK, if you're using foil you should lightly coat that.