Soften butter to room temperature. Preheat oven to 350 degrees. Beat butter and sugars in a large bowl till light and fluffy. Beat in the eggs and vanilla.

Sift in the flour, cocoa, baking soda, and salt. Add the chocolate chips and stir together till well combined.

Roll dough into balls about 2 inches across (they should weigh 2 ounces).

Place cookie dough balls at least 3" apart on silpat lined or lightly greased baking sheets. Press dough down slightly with your palm.

Bake at 350° for 12 minutes till cookies are slightly puffy and tops are dry. Cool on pans for 5 minutes then remove to wire racks to cool completely. Dust with powdered sugar.