Preheat the oven to 350 degrees.
Lightly spray a 9x11 baking pan with cooking spray. Line with parchment paper, attaching it to the sides with binder clips. Lightly spray the parchment paper.
Grind unshelled, lightly salted pistachios in a food processor. Process until you have very small pieces, but do not overdo it or you will create a nut butter. Pulse and check the texture from time-to-time.
Add the ground pistachios, flour, baking powder, baking soda, and corn starch to a large bowl. Mix with a whisk or fork.
Add the softened butter and granulated sugar to the bowl of a mixer fitted with a paddle.
Cream the butter and sugar until light and fluffy, about two minutes.
Add the vanilla and almond extracts and mix.
Add the eggs, one at a time, mixing until incorporated.
Be sure to scrape the sides and bottom of the bowl so that everything gets mixed.
Alternate adding the dry ingredients and milk, mixing between each addition. You can do this in three times each.
Again, make sure you scrape the bottom and sides.
Pour the batter into the prepared pan and bake for about 33-35 minutes, until golden brown and a wooden skewer/toothpick inserted into the center comes out clean.