1 ¼cups(283g)2 1/2 sticks salted butter, softened to room temperature
⅓cup(28g)unsweetened or Dutch-process cocoa powder
¼cup(57g)sour cream or plain yogurt
2 ¼cups(320g)all-purpose flour
2cups(340g)semisweet or bittersweet chocolate chips, regular or mini size
About ⅓cup(28g)cocoa powder, for rolling
About ⅔cup(76g)powdered sugar, for rolling
Preheat the oven to 325 degrees. Line two baking sheets with parchment paper or silpat liners.
In a large bowl using a handheld electric mixer or in a stand mixer fitted with the paddle attachment, cream together the butter and powdered sugar, adding the sugar in slowly so that it doesn’t puff everywhere and transform your kitchen into a white mess. Mix until evenly combined. Sift the cocoa powder and salt into the butter/sugar to avoid lumps and mix until well combined, 1-2 minutes, scraping down the sides of the bowl as needed.
Beat in the sour cream and vanilla extract until just combined. With the mixer on low, blend in the flour until no streaks of flour remain. Stir in the chocolate chips.
If your kitchen is very warm and the dough is hard to handle, refrigerate the dough for 30 to 60 minutes before rolling. Shape the dough into 1-inch balls and roll each ball lightly in the cocoa powder and place on the baking sheet. Do not flatten the cookies. The cookies will not spread very much (especially if the dough has been chilled).
Bake the cookies for 9-10 minutes. They will just barely be set but you don’t want to over bake or they will be dry. Let them cool on the baking sheet for 3-5 minutes and then transfer them to a wire rack to cool completely.
Once the cookies have cooled to room temperature, dip the tops or roll each cookie in powdered sugar until completely coated. Store in an airtight container in the refrigerator (they taste amazing chilled).
These cookies really are meant to be very truffle-like - just in cookie form, so they shouldn't spread much. If you find they are spreading/flattening, chill the dough or add just a touch more flour.