Using a stand mixer fitted with the dough hook attachment, mix the milk, yeast, eggs, salt, sugar, butter and flour on low until the ingredients are combined. Turn the mixer to a medium speed and mix until you see a dough beginning to form.
Use a pastry scraper to scrape any mixture left on the side of the bowl during the mixing process.
Turn the dough out onto a lightly floured workbench and knead with your hands until it comes together into a smooth ball. Grease a stainless steel or ceramic bowl with oil and add the dough.
Cover with a lid or beeswax wrap and leave in a warm place for an hour to rise (or put in the fridge for an overnight rise).
Remove the skins from the sausages and put the sausagement into a bowl. Stir in 2 tsps flour (to prevent a sticky consistency) and then roll into small balls.
Place in a hot pan and fry until sealed on each side. It doesn’t matter if the sausage balls aren’t cooked through, as they’ll be going back in the oven.
Preheat the oven to 200°C/ Gas 6. Boil 2 whole potatoes in their skins until just tender. Take out the dough, roll out two 30cm pizza bases and set aside.
In a small bowl, mix 60 ml olive oil with 2–3 minced garlic cloves and ½ teaspoon salt. Brush the garlicky oil generously over each pizza base. Add thin slices of cooked potato and divide lightly browned tiny sausage meatballs between the pizzas.
Sprinkle the pizzas with a little chopped rosemary and shavings of ricotta salata or your favourite cheese.
Bake for 15 minutes and serve with a few rocket (arugula) leaves scattered over the top.