Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a mixing bowl, combine the flour, baking powder, and salt. Whisk together and set aside.
In another bowl, cream together the softened butter, granulated sugar, and brown sugar until light and fluffy.
Add the egg and vanilla extract to the butter mixture and beat until well combined.
Gradually mix in the dry ingredient mixture until just combined.
Gently fold in the fresh raspberries, rolled oats, and nuts (if using) until evenly distributed.
Using a spoon or cookie scoop, drop generous spoonfuls of the cookie dough onto the prepared baking sheet, leaving space between each cookie.
Bake for 12-15 minutes, or until the edges are lightly golden and the centers are set.
Remove from the oven and let the cookies cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.
For added sweetness, consider drizzling a simple glaze over the cookies once cooled.