Preheat your oven to 350°F (175°C). Grease and flour an 8-inch round cake pan or line it with parchment paper.

In a mixing bowl, cream together the softened butter and granulated sugar until the mixture becomes light and fluffy.

Add the eggs, one at a time, mixing well after each addition. Then, incorporate the orange juice and orange zest, blending everything smoothly.

In another bowl, whisk together the all-purpose flour, ground pistachios, baking powder, baking soda, and salt until they are fully combined.

Gradually add the dry mixture to the wet ingredients, stirring gently until just combined. Be careful not to overmix.

Stir in the vanilla extract to enhance the cake's flavor.

Pour the batter into the prepared cake pan, smoothing the top evenly with a spatula.

Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted into the center comes out clean.

Remove the cake from the oven and allow it to cool in the pan for about 10 minutes before transferring it to a wire rack to cool completely.

Once cooled, you may choose to leave the cake plain or add a light dusting of powdered sugar for elegance.

Cut the cake into slices and arrange on a platter, garnished with chopped pistachios and orange slices or zest curls as desired.