Preheat the oven to 350°F. Line two standard muffin pans with 18 cupcake liners and set aside.

Place the shelled pistachios in a food processor or blender and process until to fine crumbs.

In a large mixing bowl, whisk together the pistachio crumbs, cake flour, baking powder, and salt. Set aside.

Combine the buttermilk, vanilla extract, and almond extract in a separate mixing bowl or measuring cup and stir together. Set aside.

In the bowl of a stand mixer fitted with the paddle attachment or in a large mixing bowl using a handheld electric mixer, beat the butter and sugar on medium speed until light and fluffy.

Add half of the flour mixture to the butter mixture and mix on low speed until just combined. Add the buttermilk mixture and mix on low speed until just combined, then mix in the remaining dry ingredients just until combined.

In a separate clean mixing bowl with clean beaters, beat the egg whites on medium speed until stiff peaks form. Gently fold the egg whites into the batter until just combined.

Divide the batter evenly between the prepared muffin pans, filling only 2/3 full.

Bake for 16 to 20 minutes or until a toothpick inserted into the center of the cupcakes comes out clean.

Remove from the oven and allow to cool in the pans for 10 minutes, then transfer to a wire rack to cool completely.

In the bowl of a stand mixer fitted with the whisk attachment, or in a large mixing bowl using a handheld mixer, add the heavy whipping cream, powdered sugar, and vanilla. Start mixing on low speed. Once the mixture starts to increase in volume, increase the speed to medium-high and mix until soft peaks form.

Add the cream cheese and continue mixing on low-medium speed until stiff peaks form. If needed, you can stop a few times and fold the frosting with a rubber spatula to make sure everything is thoroughly mixed together.

Add the frosting to a piping bag fitted with your favorite piping tip and frost the cooled cupcakes as desired.