Preheat the oven to 350°F (175°C). Line a large baking sheet with parchment paper, or grease it with a light layer of butter and dusting with flour if you don't have parchment paper. Shake off any excess flour after greasing.
In a medium bowl, whisk together the all-purpose flour, baking soda, and kosher salt.
In the bowl of a stand mixer, cream together the unsalted butter, granulated sugar, and light brown sugar until light and fluffy.
Add the vanilla extract and eggs, one at a time, beating well after each addition.
Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. This prevents over-mixing, which can lead to tough cookies. Stir in the white chocolate chips and gently fold in the frozen raspberries, being careful not to crush them and release too much moisture.
Using a large cookie scoop or tablespoon cookie scoop, portion the cookie dough into balls and place them on the prepared baking sheet. Make sure to leave enough space between each cookie dough ball to allow for spreading as they bake in the oven.
Bake the cookies in the preheated oven for 10-12 minutes, or until the edges are golden brown and the centers are just set. For best results, rotate the baking sheet halfway through baking to ensure even cooking.
Allow the cookies to cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely. This helps set the cookies and enhances their chewy texture.
Serve and enjoy!