Melt 3 tbsp of the unsalted butter in a small bowl and mix in the instant coffee. Set aside.
The mixture won’t look very pretty but you just need all of the instant coffee crystals to become hydrated so it mixes evenly into the cookie dough later.
In a medium bowl, whisk together flour, salt, sifted cocoa powder, and sifted cornstarch. Set aside.
In a large bowl, beat together the rest of the softened butter (13 tbsp) and sugar until fluffy.
Scrape down the bowl and mix in the instant coffee mixture and vanilla extract.
Fold the dry ingredients into the butter mixture. Make sure there are no dry spots – the dough will look like grainy playdough and should form into a ball easily.
Shape the dough into 4 one-inch-wide logs, place on a parchment-lined cookie sheet, and chill in the fridge for 10 minutes.
After 10 minutes, remove the dough logs from the fridge and cut them into one-inch segments.
Roll each segment into an oval bean-like shape between your hands and set it back on the cookie sheet.
To create the lines down the center that make them look like coffee beans, gently press into each cookie with a toothpick, bench scraper, or the blunt side of a small knife.
Chill the cookies in the fridge again for 30 minutes. Preheat your oven to 325°F (165°C) while the cookies chill.
After 30 minutes, arrange the cookies with one inch of space in between on parchment-lined cookie sheets.
Bake cookies for 12-15 minutes until they are a little puffed up and mostly matte.
Remove the cookies from the oven and let them cool on the tray for 10 minutes before transferring them to a wire rack to finish cooling.
