In a medium bowl whisk together the flour, cocoa powder, baking soda and salt.
In a separate large bowl beat together the butter, brown sugar and white sugar until fluffy. Beat in the egg and vanilla extract.
With the mixer on low speed, beat the flour mixture into the butter mixture about ½ at a time. The dough will be sticky. Then mix in the chocolate chips.
Cover the bowl with plastic wrap and place the bowl in the fridge for 3 hours (or overnight) .
When ready to bake, preheat the oven to 350F degrees and line cookie sheets with parchment paper or silicone baking mats.
Form the dough into balls about 1 to 1.5 tablespoons in size (a little smaller than a golf ball) and place 2 inches apart on the lined cookie sheets. I typically get around 28 cookies.
Bake in the preheated oven for 8-10 minutes, or until the tops look set.
Raspberry Cream Cheese Frosting
Add the raspberries to a blender or food processor and pulse until smooth
Pour the puree through a metal sifter to remove the seeds. Use the back of a spoon or rubber spoon to push the puree through.
Transfer the puree (without seeds) to a small saucepan over low heat. Bring the mixture to a gentle bowl while gently stirring. Continue stirring the mixture as it boils. Continue boiling the mixture until it reduces and looks thick like jam. You should only end up with a few tablespoons of reduced puree. Allow the puree to cool.
In a large bowl, beat the butter until soft. Beat in the cream cheese.
With the mixer on low speed, mix in about 1 cup of powdered sugar and salt.
Mix in 1 tablespoons of the thick raspberry puree. Make sure the puree is completely cooled.
Mix in the rest of the powdered sugar about ½ cup at a time, adding in 1 extra tablespoon of the thick raspberry puree.
Making Your Sandwiches
Frost the bottom of 1 cookie with about 1 tablespoon of frosting, then sandwich a second cookie over the top. I typically get about 14 sandwiches in total.
Notes
Chilling the cookie dough is necessary for this recipe. I typically make the cookie dough the night before and chill it overnight. Then I'll bake the cookies and make the frosting the next day.
If you're short on time, you can substitute the raspberries with 1-2 tablespoons of raspberry preserves or jam (ideally seedless). Skip steps 1-3 of making the frosting, and add the raspberry preserves in place of the reduced raspberry puree.
Store cookies in the fridge. Because the frosting is made with fresh berries, I like to store the cookies in the fridge. They'll last for 3-4 days in the fridge.
Nutrition information is an estimate only and based on 1 cookie with frosting, assuming the recipe yields 14 equal-sized sandwich cookies.