. Preheat your oven to 350°F (175°C) and grease two 8-inch round cake pans.
. In a food processor, pulse the pistachios until finely ground. Combine them with the flour, baking powder, and salt in a bowl.
. In another bowl, beat the butter and sugar until creamy. Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.
. Gradually add the dry ingredients to the wet mixture, alternating with the milk, beginning and ending with the dry mixture. Mix until just combined.
. Divide the batter evenly between the prepared pans and smooth the tops.
. Bake for 25-30 minutes or until a toothpick inserted into the center comes out clean.
. Let the cakes cool in the pans for 10 minutes, then remove them from the pans and let them cool completely on a wire rack.
. For the frosting, beat the softened butter until creamy, then add powdered sugar and vanilla extract. Mix until smooth. Finally, blend in the pistachio paste.
. Frost the cooled cakes and enjoy!