Preheat oven to 350°F (177°C). Grease three 8-inch round cake pans, line with parchment paper rounds, then grease the parchment paper.

Pulse the pistachios in a food processor until ground up into very fine crumbs.

Pour 1 and ½ cups (180g) of pistachio crumbs in a large bowl. Reserve the remaining pistachio crumbs for garnish. Whisk in the cake flour, baking powder, baking soda, and salt. Set aside.

Using a handheld or stand mixer fitted with a paddle or whisk attachment, beat the butter and sugar together on high speed until smooth and creamy, about 3 minutes.

Beat in the egg whites on high speed until combined, about 2 minutes. Beat in the sour cream, vanilla extract, and almond extract.

Add the dry ingredients, then start the mixer on low speed. With the mixer running, slowly pour in the milk (and the green food coloring, if using) and mix just until combined.

Divide batter evenly among the prepared cake pans. Bake for 21–23 minutes or until the cakes are baked through.

Allow cakes to cool completely in the pans set on a wire rack.

In a large bowl using a handheld or stand mixer fitted with a whisk or paddle attachment, beat the cream cheese and butter together on medium-high speed until smooth, about 2 minutes.

Add the confectioners’ sugar, vanilla extract, and a pinch of salt. Beat on low speed for 30 seconds, then increase to high speed and beat for 3 minutes until completely combined and creamy.

Layer off the tops of the cakes to create a flat surface. Place 1 cake layer on your cake turntable, cake stand, or serving plate. Evenly cover the top with frosting. Top with 2nd layer, more frosting, and then top with the 3rd layer.

Spread remaining frosting all over the top and sides. Decorate the sides and top of the cake with the remaining pistachios.

Refrigerate cake for at least 30 minutes before slicing.