I have seen many incarnations of this meal including mashed potato on top of a pizza base. We wanted to try something a little less calorific and found this recipe to try and adapt where necessary. As it turns out, it is gluten free due to the flours she uses.
We didn't have any sweet potato mash so used normal potato, mashing it with salt and pepper but no butter or margerine or milk - we call it dry mash!
I didn't have the spice additions to the mash she used so settled on a touch of dried tarragon - worked fine. Personally we think you would need one of these each but with little else. As it was, we got one 9" round base, which needs to be rolled reasonably thin, ours was about 1cm:
I used tomato puree watered down, followed by some sliced chilli, a little grated cheese (no mozzarella) and a few small slices of pancetta. It baked for another 10 minutes.
We ate it with grated carrot and apple (the apple provides enough of a dressing) and peas and sweetcorn.
Verdict: Very nice.
We made it again a few days later. I really must be patient and cook the base for the full 30 minutes. It has to be dry and slightly crisp or the topping makes it soggy. The pepper needed also to be cooked (and mushrooms if using) as they create too much moisture: