01 - Preheat the oven to 375°F. Line two baking sheets with parchment paper.
02 - In a large bowl, whisk together flour, cocoa powder, baking powder, baking soda, and salt.
03 - In a separate bowl, whisk granulated sugar, brown sugar, eggs, milk, sour cream or yogurt, melted butter, and vanilla extract until smooth and combined.
04 - Add the wet mixture to the dry ingredients and gently mix until just combined, taking care not to overmix.
05 - Fold the semisweet chocolate chips into the batter evenly.
06 - Using a large cookie scoop or 1/4 cup measure, drop mounds of batter onto prepared baking sheets, spacing them approximately 2 inches apart.
07 - Bake for 11 to 13 minutes, until the tops are set and a toothpick inserted in the center comes out with a few moist crumbs.
08 - Let cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.