Preheat the oven to 350°F (175°C) and line 2 cookie sheets with parchment paper or silpat mats.
Prepare the Cookie Dough: In a large bowl, cream together 1 cup of sugar and softened butter until light and fluffy (about 3 minutes). Add the egg, vanilla, and coffee granules. Beat until well combined. Add flour, cocoa powder, salt, and baking soda. Mix on low until just combined. Using a small ice cream scoop, form dough balls and roll them in the remaining 1 cup of sugar. Place them on the prepared cookie sheets, a few inches apart. Make an indentation in the center of each cookie using your thumb.
Bake the Cookies: Bake in the preheated oven for 8 minutes or until the edges are set. Allow the cookies to cool on the sheets for 3-5 minutes before transferring them to a cooling rack.
Prepare the Chocolate Ganache: In a microwave-safe bowl, heat the cream until hot but not boiling (about 1 minute). Pour the hot cream over the chocolate chips. Cover and let it sit for 3 minutes. Remove the cover and whisk until smooth. Let the ganache cool slightly, then spoon it into a piping bag (or a zip-top bag with the corner snipped off).
Fill the Cookies: Pipe dollops of ganache into the indentations of the cooled cookies.
Allow the Ganache to Set: Let the cookies sit at room temperature for about 1 hour or chill in the refrigerator for 30 minutes to allow the ganache to harden completely.
Notes
Store the cookies in an airtight container at room temperature for up to 3 days, or refrigerate for longer freshness.Get creative with the filling by using different flavored chocolates or adding a sprinkle of sea salt on top of the ganache.