Preheat the oven to 425 degrees. Line two baking sheets with parchment paper or aluminum foil sprayed with cooking spray.
Chop the chicken into bite-sized pieces, about ½ inch wide. Roughly chop the spinach into smaller pieces to ensure even distribution.
Separate one egg and add the yolk to a medium-sized bowl. Place the egg white in a small bowl to the side for later use. To the egg yolk, add ricotta cheese, garlic powder, oregano, basil, and salt. Mix well until combined.
Add the chopped spinach to the mixture and mix again until everything is well incorporated.
Divide the dough into four even pieces. Lightly flour the counter to prevent sticking. Roll each piece of pizza dough into a circle about 7 inches wide.
Spread the ricotta cheese mixture on half of each circle of dough, leaving about an inch border around the edge, dividing evenly between the calzones.
Add the chopped chicken on top of the ricotta cheese mixture, ensuring equal distribution across all calzones. Then, sprinkle mozzarella cheese on top of the chicken.
Fold the dough in half over the filling to create a half-moon shape. Starting in the center of the curve, press the edges together firmly to seal the filling inside.
Take a little bit of the dough along the edge from the bottom and roll and fold it over the top to seal the edges and give it a nice ridge.
Carefully transfer the unbaked calzones to the prepared baking sheets in a single layer.
In the bowl with the reserved egg white, crack the second egg and beat them together with a fork. Lightly brush the edges and the tops of the calzones with the egg wash.
Bake in the preheated oven until golden brown, about 15 to 18 minutes, or until they are cooked through. Optionally, top with some parmesan cheese and enjoy them hot, served with warmed marinara sauce for dipping.
