01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - Whisk together flour, salt, and espresso powder in a medium bowl until evenly blended.
03 - Beat softened butter and powdered sugar with electric mixer on medium-high speed until light and fluffy, approximately 2-3 minutes.
04 - Mix in vanilla extract until fully incorporated into butter mixture.
05 - Add flour mixture to butter mixture in two additions, mixing on low speed until just combined. Avoid overmixing.
06 - Turn dough onto lightly floured surface. Shape into rectangle approximately 1/2 inch thick.
07 - Cut into desired shapes using knife or cookie cutter. Place cookies 1 inch apart on prepared baking sheets.
08 - Bake for 16-18 minutes until edges just begin to turn golden brown.
09 - Let cookies cool completely on wire rack.
10 - Drizzle or dip cooled cookies in melted dark chocolate. Sprinkle with flaky sea salt. Allow chocolate to set before serving.