Preheat the oven to 350°F (175°C) and line baking sheets with parchment paper.
Wash, peel if desired, dice the peaches into small pieces, and gently pat them dry with paper towels.
In a large bowl, beat the butter, granulated sugar, and brown sugar until light and fluffy.
Add the eggs one at a time, then mix in the vanilla extract.
In another bowl, whisk together the flour, baking powder, salt, and cinnamon.
Gradually add the dry ingredients to the wet ingredients and mix until a soft dough forms.
Gently fold the diced peaches into the dough until evenly distributed.
Scoop the dough onto the prepared baking sheets, leaving about 2 inches between each cookie.
Bake for 10–12 minutes, or until the edges are lightly golden while the centres remain soft.
Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.