Preheat your oven to 350°F (175°C). In a food processor, pulse the shelled pistachios until finely ground, being cautious not to turn them into a paste. Measure out 1 cup of the ground pistachios for the cake, and set aside the rest for decoration later.

In a medium mixing bowl, whisk together the ground pistachios, all-purpose flour, baking powder, and salt until well combined.

In a large bowl, cream the softened unsalted butter and granulated sugar together for about 3 minutes until light and fluffy. Gradually add the eggs, mixing well after each addition until fully incorporated.

Stir in the whole milk, vegetable oil, vanilla extract, and almond extract into the butter-sugar mixture until just combined.

Gently fold the dry ingredient mixture into the wet ingredients until there are no visible streaks of flour.

Divide the batter among three greased 8-inch round cake pans. Bake for 22–25 minutes or until a toothpick inserted comes out clean. Cool in the pans for about 10 minutes before transferring to wire racks.

While the cake layers are cooling, whip the heavy cream until soft peaks form, then gently fold in the mascarpone cheese and powdered sugar until smooth.

Once the cake layers are cooled, spread frosting over the top of the first layer, add the second layer, repeat the process, and then frost the top and sides of the cake.

Refrigerate the cake for at least 2 hours before serving to enhance flavors and texture.