Prepare the Dough:

1. Preheat the Oven: Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
2. Mix Dry Ingredients: In a medium bowl, whisk together the flour, baking soda, and salt. Set aside.
3. Cream Butter and Sugar: In a large mixing bowl, beat the softened butter and granulated sugar together until light and fluffy, about 2-3 minutes.
4. Add Wet Ingredients: Add the egg and vanilla extract to the butter-sugar mixture, beating until combined.
5. Incorporate Dry Ingredients: Gradually add the dry ingredients to the wet mixture, stirring until just combined.
6. Add Raspberries: Gently fold in the mashed raspberries. Be careful not to overmix, as you want the raspberries to stay intact for bursts of flavor in the cookies.

Optional Filling:

7. Add Jam (Optional): If using, place a small dollop of raspberry jam on the center of each cookie dough ball before baking. This will create a jam-filled center when baked.

Shape and Bake:

8. Form Cookie Dough Balls: Scoop tablespoon-sized portions of dough and roll them into balls. Place them on the prepared baking sheet, spacing them about 2 inches apart.
9. Bake: Bake the cookies in the preheated oven for 12-15 minutes or until the edges are golden brown, and the centers have set.
10. Cool: 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.

Optional Finishing Touch:

11. Dust with Powdered Sugar: For an extra touch of elegance, dust the cooled cookies with powdered sugar.