Bring the stock to the boil and slowly whisk in the polenta, stirring constantly. Add a pinch of sea salt and, after a few minutes, once thickened, finely grate in the Parmesan and stir in the oregano.
Pour into a greased and lined 20cm square tin and pop in the fridge to chill and firm up, about 1 hour.
For the dip, toast the pine nuts in a dry pan, then tip into a food processor. Crush in the garlic and grate in the Parmesan, measure in 60ml of extra virgin olive oil, then add the rest of the ingredients and pulse until combined but still coarse. Season to taste, and scrape into a serving bowl.
Preheat oven to 220ºC/425ºF/gas 7.
Cut the chilled polenta into chips and brush with 2 tablespoons of olive oil. Dust with the extra polenta. Arrange on a greased baking tray in a single layer and bake for 30 minutes, or until crisp and golden.
Serve the hot polenta chips with some extra Parmesan grated on top, and the pesto dip on the side.