Combine fresh raspberries with a touch of sugar in a bowl and crush until you achieve a thick, semi-smooth puree.

In a large mixing bowl, whisk together all-purpose flour, baking soda, and salt until well combined.

Cream together the softened unsalted butter and sugar until light and fluffy, then add egg and vanilla extract.

Gradually add the dry ingredient mixture to the wet ingredients until a smooth cookie dough forms.

Gently fold the raspberry puree into the cookie dough for a marbled effect.

Preheat your oven to 350°F (175°C) and scoop the cookie dough onto lined baking sheets.

Bake for 10-12 minutes, or until edges are golden brown and centers are set.

Let them cool on the baking sheet for about 5 minutes, then transfer to a wire rack.