Preheat oven to 325°F (165°C). Line two large baking sheets with parchment paper and lightly spray with non-stick spray.

In a medium bowl, whisk together flour, cocoa powder, baking powder, and salt. Set aside.

In a large microwave-safe bowl, melt the semi-sweet chocolate and butter in 15-second increments, stirring between each, until smooth.

Whisk in vanilla, then add both sugars and orange zest. Stir until well combined.

Beat in eggs one at a time, mixing well after each. Stir in milk.

Gradually add the dry ingredients to the wet ingredients and mix until just combined. Do not overmix.

Fold in chopped orange chocolate.

Cover and chill dough for 30 minutes.

Using a 1/4 cup measure, scoop dough onto prepared baking sheets, spacing them apart.

Bake one tray at a time. Once cookies go into the oven, reduce heat to 300°F (150°C).

Bake for 16 to 19 minutes, or until edges are set and tops are dark and shiny.

Press reserved orange chocolate chunks into tops of warm cookies if desired.

Allow cookies to cool completely on baking sheet before serving.