Everyone is different so you would have to test your own bodies reactions, some people do react to the natural sugars in milk/cheese. Luckily I don't but I will get a small rise in BGL if I eat a lot of cheese, I do love cheese
I use celeriac and cauliflower cooked together for the topping I season it and mash it up with some grated cheese. Some use sweet potato and they are good with it so ok if you can eat it without raising your BG you would have to test to know that
Using cauliflower instead of potato is a very nice substitute that I used to use. To be fair very few people noticed the difference in my shepherds pie when I used cauliflower instead of potato and it was always popular at pot lucks etc.
Hi i use a mixture of sweet potato and celeriac then cover in a mixture of hard cheeses whatever i have in then cook on high in oven on a high heat delicious