With an electric mixer, cream cold butter and sugar until smooth. If you need to let it warm up a bit, feel free, but I have had more luck with these with my butter still cold.
Add the eggs and vanilla and mix well.
Add in flour, cocoa, salt and baking soda until combined.
Stir in the chocolate chips, white chocolate chips and frozen raspberries (do not let thaw*). Cover bowl with plastic wrap and let dough chill in the freezer for 30 minutes.
Preheat oven to 350℉.
Shape dough into approximately 1½" balls and place on a parchment lined baking sheet. Bake for 12-15 minutes until the tops are set and no longer glossy. (The exact bake time will vary depending on the size of your cookies).
Allow to cool completely on the baking sheet before removing.
Notes
*Keeping the raspberries frozen prevents them from becoming complete mush. They will still break and smush a little bit as you mix them in -- do not worry. I prefer it this way because the raspberry flavour is spread more evenly throughout the cookie, but you will still have some chunks of raspberry.