Preheat the oven to 350°F (175°C). Line two baking sheets with parchment paper or silicone baking mats.
In a medium bowl, whisk together the all-purpose flour, malted milk powder, unsweetened cocoa powder, baking powder, and salt; set aside.
In a large bowl, cream the unsalted butter and granulated sugar with a hand mixer or stand mixer on medium speed until very smooth, about 3 minutes.
Add the eggs one at a time, beating about 1 minute after each addition, then beat in the vanilla extract.
Reduce mixer speed to low and add half of the dry ingredients, mixing just until incorporated. Add the whole milk and then the remaining dry ingredients, mixing only until combined.
With the mixer on low or using a rubber spatula, fold in the coarsely chopped malted milk balls and the chocolate chips until evenly distributed.
Drop heaping 2-tablespoon portions of dough (or use a large cookie scoop) onto the prepared baking sheets, leaving about 2 inches between cookies.
Bake for 10 to 12 minutes, until cookies are puffed and set but still slightly soft to the touch.
Let the cookies rest on the baking sheet for 2 minutes, then transfer to a cooling rack to cool to room temperature.