In a medium bowl, whisk together the flour, baking powder, salt, cinnamon, and nutmeg. Set aside.

In a large mixing bowl, use an electric mixer to cream together the sugar, butter, and orange zest until the mixture is light and fluffy—about 2 minutes.

Add the ricotta and egg to the bowl, beating until well incorporated.

Slowly incorporate the dry ingredients into the wet mixture, mixing just until everything is blended.

Fold in the chopped chocolate and pistachios by hand using a spatula.

Cover the bowl tightly with plastic wrap and chill in the refrigerator for a minimum of 1 hour or up to 24 hours.

Preheat your oven to 350°F and line a baking sheet with parchment paper.

Scoop out about 1 1/2 tablespoons of dough per cookie, roll into balls, and place on the baking sheet 2 inches apart.

Bake for 12 to 14 minutes, or until the bottoms are just beginning to brown. Note: cookies will not darken much on top.

Allow the cookies to rest on the baking sheet for 5 minutes, then move them to a wire rack to finish cooling.

Once cooled, drizzle melted chocolate over each cookie. Alternatively, you can dust them with powdered sugar.