Mix together flour, espresso powder, and salt
Using the paddle attachment of a stand mixer, cream together butter and icing sugar. Add vanilla, cacao nibs, and chocolate chips and mix until just combined
Add dry ingredients and continue mixing until dough comes together
Scrape dough onto non-stick or flour covered work surface. Divide in half. Roll each half into equal size logs
Sprinkle cocoa powder on the work surface and roll each log in the powder
Tightly wrap each log in plastic wrap and chill at least 2 hours
Preheat oven to 350 F. Slice cookies into approximately 1/4" thick rounds Place on parchment lined baking sheets
Bake for 18-20 minutes until just firm. Cool on wire rack.