Preheat the oven to 200-225'C (200 if fan assisted)
Get a large pan of cold water, add a large pinch of salt and put on a medium heat.
While the pan of water is heating up peel and chop your potatoes. In my house we all like the smaller crispy ones so I cut each potato to roughly the size of a small egg.
By the time you've peeled and chopped your potatoes the water should be warm, not boiling. Add the potatoes to the pan at this stage and allow to heat to a slow simmer. This should take around 7 minutes.
Get a large roasting tray, the wide shallow ones are better than the smaller deep ones as if the potatoes are too cramped they won't brown.
Line the tray with a sheet of baking paper... this may seem like a step which you can leave out, but trust me it's so much easier if you do it! (cleaning and cooking wise).
Drizzle the olive oil onto the baking tray (lined with baking paper) and place the potatoes onto the tray. Next scatter the polenta on top.
Just shaking the pan doesn't do a great job of coating each potato in oil and polenta, so I tend to lift each side of the baking paper up in turn to roll the potatoes over each other. I find this coats them better and they also don't break up so much (especially if you've used over ripe fluffy potatoes which can crumble easily).
Season with salt and pepper and put in the oven for 30-40 minutes.
Notes
You can use any potatoes for this recipe.
I've used cheap 'white potatoes', maris piper, disiree, and even new potatoes which needed to be used up.