Preheat your oven to 350°F (175°C). Finely grind the pistachios in a food processor until they resemble a coarse flour.

In a large mixing bowl, beat together the softened butter, vegetable oil, and granulated sugar until light and fluffy, about 3-4 minutes.

Incorporate the eggs one at a time, followed by the vanilla extract until the mixture is smooth and creamy.

In a separate bowl, whisk together the flour, baking powder, and ground pistachios. Gradually add this dry mixture to the wet mixture, alternating with milk and sour cream.

Spoon the batter into cupcake liners about two-thirds full. Bake for 15-18 minutes until a toothpick inserted comes out clean.

Allow the cupcakes to cool in the pan for 5-10 minutes before transferring to a wire rack to cool completely.

In a medium bowl, beat together the cream cheese and butter until smooth. Gradually add powdered sugar until desired thickness is reached.

Frost the cooled cupcakes generously with cream cheese frosting and optionally sprinkle chopped pistachios on top.