01 - 
                Preheat oven to 260°C (500°F).
              
              
              
                02 - 
                In a large bowl, combine spinach, ricotta, mozzarella, olive oil, egg yolk, garlic powder, oregano, red pepper flakes, and salt. Mix thoroughly until well incorporated.
              
              
              
                03 - 
                Place dough on a lightly floured surface and divide into 4 equal portions.
              
              
              
                04 - 
                Flatten each piece of dough into a 18cm (7-inch) round on pieces of parchment paper, using either a rolling pin or your hands.
              
              
              
                05 - 
                Spread one-quarter of the spinach filling evenly over half of each dough round, leaving a 2.5cm (1-inch) border around the edge.
              
              
              
                06 - 
                Brush the edges with egg wash, then fold the empty half of dough over the filling, leaving the bottom 1.25cm (½-inch) border uncovered. Press edges together and pinch with fingers to seal completely.
              
              
              
                07 - 
                Using a sharp knife, cut 5 small steam vents in the top of each calzone. Brush tops thoroughly with egg wash.
              
              
              
                08 - 
                Transfer calzones on parchment paper to a baking sheet and bake for 8 minutes.
              
              
              
                09 - 
                Remove calzones from oven, brush with any remaining egg wash and sprinkle with grated Parmesan. Return to oven and bake for an additional 7 minutes until golden brown.
              
              
              
                10 - 
                Transfer to a wire rack and let cool for 5 minutes before serving to allow filling to set.