How to Make It
Preheat a large baking sheet in a 500° oven for 10 minutes and carefully spray it with oil. Meanwhile, on a lightly floured work surface, roll or stretch each ball of dough into a 9-inch round.
In a medium bowl, combine the chiles, 1 3/4 cups of the cheddar, the pimientos, a pinch of salt and 1/4 teaspoon of pepper; mash to a coarse paste with a fork.
Arrange the ham on the bottom half of each dough round. Top with the arugula and season lightly with salt and pepper. Spread the chile-cheddar mixture over the arugula to within 1/2 inch of the edge, pressing it slightly to compact. Fold the top half of the dough over the filling, pressing to release any trapped air; pinch the edges to seal.
Transfer the calzones to the prepared baking sheet. Sprinkle the remaining 1/4 cup of cheddar on top and bake for 8 minutes, or until golden and crisp.