In a stand mixer fitted with a paddle attachment, cream together butter and sugars until light and fluffy.
STEP 2
Gradually blend in the flour and chocolate mixture until fully incorporated.
STEP 3
For best results, scrape the dough into an airtight container and refrigerate for at least 3 to 4 hours or overnight.
STEP 4
When ready to bake, preheat the oven to 350°F and position a rack in the center of the oven. Line a baking sheet with parchment paper.
STEP 5
Drop the dough in 1/4-cup balls onto the prepared baking sheet, spacing them about 2 inches apart. Press the dough down slightly with the palm of your hand.
STEP 6
Bake for 20 to 24 minutes, rotating the baking sheet midway through the baking time until the cookies are deep golden brown all the way through.
STEP 7
Remove the cookies from the oven and let cool on the baking sheet for 5 to 10 minutes, then transfer them to a rack to cool completely.
STEP 8
The cookies can be stored in an airtight container at room temperature for up to 3 days.