01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - In a large bowl, cream together softened butter, granulated sugar, and brown sugar until light and fluffy, about 2 minutes.
03 - Beat in eggs one at a time, then stir in vanilla extract until fully blended.
04 - Whisk together flour, cocoa powder, baking soda, and salt in a separate bowl.
05 - Gradually add dry ingredients to the wet mixture, stirring just until combined to avoid overmixing.
06 - Fold in semi-sweet chocolate chips evenly throughout the dough.
07 - Scoop dough by rounded tablespoons onto prepared baking sheets, spacing cookies adequately.
08 - Bake for 11 to 13 minutes until edges are set but centers remain soft.
09 - Allow cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.
10 - Beat softened butter until creamy. Gradually add powdered sugar, then milk, vanilla extract, and a pinch of salt, mixing until smooth and fluffy.
11 - Once cookies are fully cooled, evenly spread or pipe a generous layer of frosting on each cookie. Decorate with sprinkles or chocolate shavings if desired.
12 - Allow frosting to set before serving to ensure optimal texture.