Step 1: Preheat your oven to 350°F (175°C) and line a 12-cup muffin tin with paper liners.
Step 2: In a medium bowl, whisk together the flour, ground pistachios, baking powder, and salt until well combined.
Step 3: In a large bowl, cream the softened butter and granulated sugar together until light and fluffy, about 3-5 minutes.
Step 4: Beat in the eggs one at a time, followed by the orange zest. Ensure each egg is fully incorporated before adding the next.
Step 5: Mix the orange juice and milk together in a small jug.
Step 6: Alternately add the dry ingredients and the milk mixture to the butter mixture, beginning and ending with the dry ingredients. Mix until just combined.
Step 7: Scoop the batter into the prepared muffin liners, filling each about 2/3 full.
Step 8: Bake for 18-22 minutes, or until a skewer inserted into the center of the orange pistachio cupcakes with rosewater icing comes out clean.
Step 9: Allow the cupcakes to cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.
Step 10: To make the icing, whisk the powdered sugar, rosewater, and 1 tablespoon of orange juice until smooth. Adjust consistency with more juice or sugar if needed.
Step 11: Drizzle or spread the icing onto the cooled orange pistachio cupcakes with rosewater icing and top with crushed pistachios.