01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - Whisk together flour, baking soda, and salt in a medium bowl. Set aside.
03 - Beat butter, granulated sugar, and brown sugar in a large bowl until light and creamy, approximately 2 minutes.
04 - Add eggs one at a time, beating thoroughly after each addition. Mix in vanilla extract and sour cream until fully combined.
05 - Gradually incorporate dry ingredients into wet mixture, mixing just until flour disappears.
06 - Gently fold white chocolate chips and diced peaches into dough until evenly distributed.
07 - Drop rounded tablespoonfuls of dough onto prepared baking sheets, leaving 2 inches of space between each cookie.
08 - Bake for 11 to 13 minutes until edges turn golden brown and centers are set.
09 - Let cookies rest on baking sheets for 5 minutes, then transfer to wire rack to cool completely.