I made this today to use as the top layer on lasagne.
I copied Maddy's tweaks of using 200g of cheese (160g Vintage cheddar and 40g tasty) and 45g cornflour.
I started to cook on speed 4 as per recipe, but after a few seconds of it blitzing everything, I turned down to speed 3 and left the MC off. At the end of cooking time, I removed the bowl from the housing and let sit for 3-4 mins while I was getting the lasagne ready for the final layer. The sauce had thickened to a perfect smooth consistency and was easy to pour/spread over the top. I've put the rest in a freezer container for another time.
I totally agree with everyone's view that it tastes wonderful. This will be my go to one now too.