Finely grind shelled pistachios in a food processor until they reach a fine powder, similar to almond meal.

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

In a large mixing bowl, beat softened unsalted butter and granulated sugar until light and fluffy.

Add room temperature eggs one at a time, then pour in the whole milk, vegetable oil, vanilla extract, and optional almond extract.

Gently fold the dry mixture into the wet mixture until just moistened.

Preheat your oven to 350°F (175°C). Divide the batter among three greased 8-inch round cake pans and bake for 22-25 minutes.

Cool the cake layers in the pans for 10 minutes, then transfer to a wire rack to cool completely.

Whip heavy cream until soft peaks form, then add mascarpone cheese, powdered sugar, and vanilla extract and mix until smooth.

Assemble the cake by spreading mascarpone cream between each layer and frosting the top and sides.

Refrigerate the assembled cake for at least two hours before serving and sprinkle chopped pistachios on top.