Preheat oven to 180°C. Peel the sweet potatoes and chop up roughly into chunks. Chuck them in a roasting tray, lash some olive oil onto them to coat, season and roast for about 45 minutes until starting to caramelize and tender. You may toss them around, halfway through cooking, so that they brown evenly.
Cook the pasta in boiling water until tender. Drain and rinse well under cold water, then pour a bit of olive oil on the shells and mix well. The oil will stop the pasta from sticking together. Season lightly.
Heat the butter in a small saucepan until melted and hot. Have a plate with some paper-towel ready.
Fry the sage leaves (a few at a time) for about five to ten seconds until crisp. Remove them carefully with a fork and drain on the paper-towel. If the butter gets too hot, it will brown and burn the sage leaves, so heat gently, but do be careful not to burn the hell out of them.
Chop up the haloumi into small chunks and fry in a non-stick frying pan in a tablespoon of olive oil. This only takes a minute or two and all you want is for the haloumi to turn a golden colour. It is very handy and won’t melt away or go gooey.
When the sweet potatoes are cooked, cool slightly and then toss in the pasta and haloumi. Season with more olive oil, if necessary, and plenty of black pepper. The haloumi is fairly salty, so go easy on the salt.
Put the sage leaves on top and serve whilst still warm.