Step 1: Preheat your oven to 350°F (175°C). Grease a 9-inch round cake pan and line the bottom with parchment paper.
Step 2: In a medium bowl, whisk together the flour, baking powder, baking soda, cinnamon, ginger, and salt until well combined.
Step 3: In a large bowl, beat the eggs with granulated and brown sugar until the mixture is pale and thick.
Step 4: Gradually pour in the vegetable oil and vanilla extract while continuing to whisk, then stir in the orange zest and orange juice.
Step 5: Gently fold the dry ingredients into the wet ingredients until just combined, being careful not to overmix.
Step 6: Stir in the finely grated carrots and 3/4 cup of the chopped pistachios until evenly distributed.
Step 7: Pour the batter into the prepared pan and bake for 40-45 minutes, or until a toothpick inserted into the center comes out clean.
Step 8: Allow the cake to cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.
Step 9: For the glaze, whisk together the powdered sugar, rose water, and enough milk or water to reach a thick yet pourable consistency.
Step 10: Pour the glaze over the cooled cake, allowing it to drip down the sides. Sprinkle with the remaining pistachios and dried rose petals before the glaze sets.