Place cauliflower, potatoes & garlic in a medium to large saucepan.
Add cream, stock & water to veg - top with more water if needed to just cover the veg.
Bring to the boil, once boiling turn down to a simmer, and simmer for 10 mins or until vegetables are tender enough to be pierced with a knife while still in the pot.
Using a slotted spoon, transfer the cauliflower, potato & garlic to the bowl of food processor, or to a bowl if you are going to just mash them (see note) allowing most of the liquid to drain off each spoonful and reserving the liquid.
Process until veg is starting to puree.
Add butter, salt & about 2 - 3 tbsp (1 tbsp at a time) of the cream/stock mixture (see note) and then keep processing until the mixture reaches a puree.
If you would like your puree smoother at this point you could pass it through a fine sieve - the finer the sieve, the smoother the puree.
Add parmesan, mixing to melt & combine.
Meanwhile, if making the cauli bacon crumb to serve, heat the extra tsp of butter in a small non-stick fry pan.
Add bacon, breadcrumbs & any reserved cauliflower "crumbs" and fry over medium high heat until crisp.
Sprinkle the puree with the cauli bacon crumb, extra parmesan and top with extra melted butter if you wish and serve.