01 - Preheat the oven to 350°F. Line two baking sheets with parchment paper.
02 - In a medium bowl, whisk together flour, salt, and espresso powder until evenly blended.
03 - In a large bowl, cream the softened butter and powdered sugar with an electric mixer until light and fluffy, about 2-3 minutes.
04 - Mix in the vanilla extract until fully incorporated.
05 - Add the flour mixture to the butter mixture in two additions, mixing on low speed until just combined. Do not overmix.
06 - Turn the dough out onto a lightly floured surface and shape into a rectangle about 1/2 inch thick.
07 - Cut into desired shapes using a knife or cookie cutter. Arrange on prepared baking sheets, spacing 1 inch apart.
08 - Bake for 16-18 minutes, or until edges are just starting to turn golden.
09 - Cool completely on a wire rack.
10 - If desired, drizzle or dip cooled cookies in melted dark chocolate and sprinkle with flaky sea salt. Allow chocolate to set before serving.