Preheat your oven to 350°F (175°C) and prepare baking sheets with parchment paper.

In a stand mixer, cream together unsalted butter, brown sugar, and granulated sugar until light and fluffy. Add egg and vanilla, mixing until combined.

In a separate bowl, whisk together flour, cornstarch, baking soda, baking powder, salt, and cinnamon. Gradually add this dry mixture to the wet mixture.

Gently fold in chopped pistachios and white chocolate, reserving some for topping.

Using a cookie scoop, portion out dough balls onto baking sheets, spacing them apart, and press reserved toppings on each ball.

Bake for 10-12 minutes or until edges are golden and centers remain soft.

Let cool on baking sheets for 10 minutes before transferring to a wire rack to cool completely.