Prepare the Pistachios by grinding shelled pistachios in a food processor until finely ground, being careful not to turn them into a paste.

Mix Dry Ingredients by whisking together ground pistachios, all-purpose flour, baking powder, and salt.

Cream Butter and Sugar by beating softened unsalted butter and granulated sugar until light and fluffy. Gradually add in eggs.

Incorporate Wet Ingredients by pouring in whole milk, vegetable oil, and vanilla extract into the butter-sugar-egg mixture.

Combine All Ingredients by gently folding the dry ingredient mixture into the wet mixture until just combined.

Bake the Cake Layers by dividing the batter among three greased and parchment-lined 8-inch cake pans and bake at 175°C (350°F) for 22-25 minutes.

Cool the Layers for about 10 minutes in the pans before transferring to a wire rack to cool completely.

Prepare the Mascarpone Cream by whipping heavy cream until soft peaks form and folding in mascarpone cheese and powdered sugar.

Assemble the Cake by layering the cooled cake with mascarpone cream and frosting the top and sides.

Garnish and Chill by sprinkling chopped pistachios on top and refrigerating for at least two hours.