Prepare the dough: Lightly dust your work surface with flour. Place the pizza dough on the surface and roll it into a rough rectangle, about 1 cm thick. You should hear a slight pop as the air pockets collapse. Cut the dough into 8 equal squares using a sharp knife or pizza cutter. The dough should feel cool and slightly springy to the touch.

Fill the donuts: Spoon a heaped teaspoon of Nutella into the centre of each dough square. Do not overfill — you want a generous amount, but if too much spills out, the donut will leak during frying. The Nutella should look like a small, dark mound in the middle of the pale dough.

Seal the edges: Fold each square in half to form a triangle, or bring all four corners to the centre to create a ball. Pinch the seams firmly together until you feel the dough seal completely and no filling peeks through. Gently roll each parcel between your palms to form a smooth ball. The surface should feel taut and smooth, with no sticky gaps.

Heat the oil: Pour the vegetable oil into your large frying pan so it reaches about 1.5 cm up the sides. Heat over a medium-high flame. To test if the oil is ready, drop a small scrap of dough into the pan — it should sizzle immediately and rise to the surface within 30 seconds, turning a light golden colour.

Fry the donuts: Carefully place 4 donuts into the hot oil, seam-side down. Do not crowd the pan. Fry for 2-3 minutes until the underside is a deep golden brown and the dough looks puffed up. You should hear a steady, gentle sizzle — if it's too loud, the oil is too hot. Flip them using a slotted spatula and fry for another 2-3 minutes. The finished donuts should be uniformly golden brown all over and feel light and airy when lifted.

Coat the donuts: While the donuts are still warm, use a pastry brush (or your fingers) to coat each one lightly with melted butter. In a small bowl, mix the caster sugar and cinnamon. Roll each buttered donut in the cinnamon sugar until fully coated. The sugar should stick immediately, creating a speckled, sparkly crust that smells like a bakery.

Serve immediately: Place the donuts on a serving plate. The centres will be molten hot, so let them rest for 2 minutes before biting into one. You'll see the Nutella ooze out slightly when you tear the donut open, leaving a rich, chocolatey trail on the plate.