Set your oven to 400°F (200°C). Line a large baking sheet with parchment paper.
Lightly flour your work surface. Divide the pizza dough into four equal portions and roll each into an 8-inch (20 cm) circle.
In a large mixing bowl, combine shredded chicken, Alfredo sauce, mozzarella, Parmesan, garlic powder, Italian seasoning, and spinach. Stir until evenly coated.
Spoon a generous scoop of filling onto one half of each dough circle, leaving a small border around the edge.
Fold the dough over to form a half-moon shape. Press edges together firmly, then crimp with a fork to seal.
Place calzones onto the prepared baking sheet. Brush tops with beaten egg for a shiny golden finish. Cut a small slit in the top of each calzone to allow steam to escape.
Bake for 20–25 minutes, or until calzones are golden brown and the filling is bubbly.
Allow to cool for 5 minutes before serving – the filling will be piping hot inside.
