01 - Preheat the oven to 350°F. Line a 12-cup muffin tin with paper liners.
02 - Process 4.2 oz pistachios in a food processor until finely ground. Reserve 1-2 tbsp for garnish.
03 - Sift flour, baking powder, and salt into a bowl. Stir in the ground pistachios until evenly distributed.
04 - Beat the softened butter and granulated sugar in a large bowl until light and fluffy, approximately 3 minutes.
05 - Incorporate eggs one at a time, beating thoroughly after each addition. Mix in vanilla extract.
06 - Add the dry mixture in two batches, alternating with milk, beginning and ending with the dry ingredients.
07 - Distribute the batter evenly among the prepared cupcake liners.
08 - Bake for 18-20 minutes until a toothpick inserted in the center comes out clean. Allow to cool completely.
09 - Finely grind 3.5 oz pistachios for the frosting. A slightly coarse texture may be retained for added crunch.
10 - Beat the butter until smooth and creamy. Gradually incorporate powdered sugar, beating until fully combined.
11 - Mix in ground pistachios, vanilla, salt, and 2 tbsp milk. Beat until fluffy, adjusting consistency with additional milk if needed.
12 - Pipe or spread the buttercream onto cooled cupcakes. Sprinkle with reserved ground pistachios.