01 - Preheat oven to 350°F and line two baking sheets with parchment paper
02 - In a medium bowl, whisk together flour, salt, and espresso powder until evenly distributed
03 - In a large bowl, beat softened butter and powdered sugar with electric mixer until light and fluffy, approximately 2-3 minutes
04 - Mix vanilla extract into the butter mixture until fully incorporated
05 - Add flour mixture to butter mixture in two additions, mixing on low speed until just combined. Do not overmix
06 - Turn dough onto lightly floured surface and shape into a rectangle about 1/2 inch thick
07 - Cut into squares or rectangles, or use cookie cutter. Arrange on prepared baking sheets with 1 inch spacing between cookies
08 - Bake for 16-18 minutes until edges are just beginning to turn golden brown
09 - Let cookies cool completely on 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