In a large mixing bowl, combine butter and sugar. Then add the egg and beat until uniform. Next, add the instant coffee and mix again.
Add the baking powder and salt. Using a sifter, add the flour and cocoa powder. Then mix until a dark cookie dough is created.
Scoop the dough into rounds on a pan lined with plastic. Cover and chill in the freezer for 30 minutes or fridge for 1 hour.
Preheat the oven to 350°F. Remove chilled cookies and place on a parchment paper lined baking sheet. Bake for 15-18 minutes.
When finished baking, remove from the oven and let cool. When the cookies have deflated a bit (about 5 minutes), use a spoon to make a small depression on the top and pipe on some dulce de leche. You could just add scoops if you don’t care about the looks.
Finish each cookie with a sprinkle of salt and enjoy!