Preheat your oven to 350°F (175°C).
In a large mixing bowl, cream the softened butter, granulated sugar, and brown sugar until light and fluffy.
Add the eggs one at a time, beating well after each addition. Then mix in the pistachio pudding mix.
In a separate bowl, whisk together the flour, baking soda, and salt.
Gradually add the dry mixture to the wet ingredients, stirring until just combined. Do not overmix.
Fold in any desired chocolate chips or nuts at this stage.
Drop spoonfuls of dough onto ungreased baking sheets, spaced about 2 inches apart.
Bake for 10-12 minutes or until the edges are lightly golden but the centers remain soft.
Allow the cookies to cool on the baking sheets for 5 minutes before transferring them to wire racks to cool completely.