Method

• 1.
  For the Neapolitan-style pizza dough, mix yeast and water in a bowl and set aside for 5 minutes or until foamy. Place flour in a large bowl and make a well. Pour in the yeast mixture and mix until dough comes together. Add 3 tsp salt flakes and knead lightly to incorporate.
• 2.
  Turn dough onto a lightly floured surface and knead vigorously for up to 10 minutes or until smooth, shiny and elastic. (If you have a stand mixer fitted with a dough hook, by all means use it instead of your muscle power!)
• 3.
  Place dough in a bowl and dust with semolina, then cover with a damp tea towel and set aside for 30 minutes to rest. Using floured hands, stretch dough into a large rectangle, then fold the top and bottom thirds into the centre, like folding a letter, and then onto itself into a ball.
• 4.
  Place in an oiled container fitted with a lid (make sure the container is large enough to allow plenty of room for rising). Cover and set aside at room temperature for 2 hours, then place in the fridge overnight (or for up to 4 days), to slow-prove and develop flavour and texture.
• 5.
  When ready to use, remove the dough from the fridge and take off the lid. Cover loosely with a tea towel and set aside at room temperature for 2 hours.
• 6.
  Preheat oven to 250°C. Place a 30cm pizza tray or round baking tray upside-down in the oven to heat up.
• 7.
  Divide dough into two even balls. Place one ball on a lightly floured surface. Using your fingers (not a rolling pin, as you want to avoid crushing the air bubbles that have formed during fermentation), stretch the dough into a 25-27cm round. Create a 1cm rim of dough around the edge to contain the filling. Place on a sheet of baking paper dusted with semolina.
• 8.
  Place half the tomato, ricotta and ’nduja onto one half of the dough round. Season with salt flakes and drizzle with a little oil. Fold the other half of the dough over to enclose, pinching edges to seal. Drizzle with oil and season with salt flakes.
• 9.
  Carefully remove the hot tray from the oven, slide the calzone (on its baking paper) onto the tray and immediately return to the oven. Do this as quickly as you can to avoid losing heat from the tray. Bake for 15 minutes, then open the oven door and carefully remove the baking paper. Quickly close the oven door and bake for a further 5 minutes or until the crust is nicely puffed up and slightly charred. Sprinkle with salt. Set aside and keep warm.
• 10.
  Repeat with remaining dough and filling to make second calzone. Serve at once.