Preheat oven to 375°F (190°C). Line two baking sheets with parchment paper or silicone baking mats.
In a medium bowl, whisk together flour, salt, and baking soda. Set aside.
Using an electric mixer on medium speed, beat softened butter with granulated and brown sugar until light and fluffy, about 2-3 minutes.
Add egg and vanilla extract to butter-sugar mixture and mix well until fully incorporated.
Reduce mixer speed to low. Gradually add flour mixture, mixing just until combined. Do not overmix.
Gently fold in diced peaches and peach preserves until just combined. Dough will be soft and slightly sticky.
Using a cookie scoop or two spoons, drop tablespoonfuls of dough onto prepared baking sheets, leaving 2 inches between cookies.
In a small bowl, mix sanding sugar and cinnamon. Sprinkle about ⅛ teaspoon over each cookie.
Bake for 11-13 minutes until edges are golden brown and centers are just set. Refrigerate remaining dough between batches if baking multiple sheets.
Cool on pans for 5 minutes, then transfer to wire racks to cool completely.
