Step 1: Preheat your oven to 350°F (175°C) and grease a 9-inch loaf pan or cake tin with butter and a light dusting of flour.
Step 2: In a medium bowl, whisk together the flour, ground pistachios, baking powder, cardamom, and salt until well combined.
Step 3: In a separate large bowl, cream together the softened butter and sugar until the mixture is light and fluffy, about 3-5 minutes.
Step 4: Add the eggs one at a time to the butter mixture, beating well after each addition to ensure a smooth base for your orange cardamom pistachio tea cake.
Step 5: Stir in the orange zest and orange juice. The mixture might look slightly curdled, but it will come together once the dry ingredients are added.
Step 6: Gradually add the dry ingredients to the wet ingredients, folding gently with a spatula until no streaks of flour remain.
Step 7: Pour the batter into the prepared pan and sprinkle the chopped pistachios evenly over the top.
Step 8: Bake for 45-50 minutes, or until a toothpick inserted into the center comes out clean.
Step 9: Allow the cake to cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.