I came across this method in a Paleo or low carb list on Facebook. Thought it was worthy of sharing.
Slowly melt cream and cheese together. Add a litle Dijon Mustard if liked.
I used 2 dessertspoons of cream to about double that amount of cheese. I also bought my cheese grated and some people say it has flour coating so the cheese does not clump together. I found the cheese thickened the sauce.
This amount would be enough for a small cauliflower cheese.
I have no carb count for you as this would depend on the cream and the cheese you use.