Preheat oven to 385 degrees Fahrenheit.
In a large mixing bowl, cream together butter, brown sugar, and sugar for about 4 minutes or until fluffy.
Fold in egg and vanilla, mixing for an additional minute.
Fold in flour, cornstarch, baking soda, and salt. Be careful not to overmix to avoid creating too much gluten.
Gently fold in freeze-dried raspberries and white chocolate. Avoid overmixing to prevent breaking up the raspberries too much.
Use a cookie scoop or spoon to form the dough into approximately 2 1/2-ounce balls. Place them on a parchment paper-lined, light-colored baking sheet.
Bake for about 9 minutes. Once done, remove from the oven. For a gourmet touch, press additional freeze-dried raspberries and white chocolate onto the tops of the cookies.
Store the cookies in an airtight container for several days. If you wish to freeze them, place them in a freezer-safe Ziploc gallon-sized bag.