Preheat oven to 180 °C (350°F) (see note 4 if using a fan function) and grease and/or line two 8 inch cake tins (I use my homemade cake release). Add your pistachios to a food processer, and process until they become fine crumbs (see note 6). Once done, set aside for now.
In a bowl, sift together your flour, cornstarch, baking soda, baking powder and salt. Using a whisk or fork, mix until well combined. Set aside.
In another bowl, add in butter, vegetable oil and sugar. Using an electric mixer (hand or stand mixer are both fine - see note 2), cream together for 2 minutes until light and creamy.
Add in eggs one by one, mixing well in between each addition (about 10-15 seconds between eggs).
Add in your vanilla, almond essence/extract, vinegar and half of the buttermilk, and mix until well combined. Now set your mixer aside as the remainder of the batter will be finished by hand.
Add half of your premixed dry ingredients to your wet mixture, and gently fold it in with a spatula until just combined. Then add in the remaining buttermilk, and fold it in until just combined. Lastly, add in the remaining dry ingredients and gently fold it into the mixture until just combined. Do not overmix (see note 3).
Finish off by adding in the crushed pistachios, and a few scant drops of green coloring (if using gel colours then use less - you only want a pastel green color), and fold with a spatula until just combined. Add more coloring if needed, but try not to overmix the batter.
Distribute the batter evenly into the two 8 inch cake tins, and bake for 40-45 minutes or until a toothpick comes out clean or with a few moist crumbs on it.
Once baked, allow the cake layers to cool in the cake tins for about 15-20 minutes, and then turn them out onto a wire rack to completely cool before frosting with the pistachio cream cheese recipe below.