In a stand mixer with a paddle attachment, beat the butter on medium-high until fluffy (about 2-3 minutes). Add the caster and brown sugar and continue beating for another minute to incorporate it. Turn the mixer down to medium-low, and add in the eggs, vanilla extract, salt, and black garlic. Continue beating for another 30 seconds, or until well-combined. (The black garlic won’t mix thoroughly, so little specks or clumps of it perfectly okay.)
Sift the flour, baking powder, baking soda, and espresso powder into the same mixing bowl. Then, incorporate this into the stand mixer in three batches, mixing it for a few seconds in between each addition.
Finally, add in the chocolate chips, and mix it on low for 10 seconds, or until well-distributed. Refrigerate the cookie dough in the fridge for at least an hour, or up to 2 days. This allows the gluten in the dough to develop, and also helps the cookie develop a deeper flavour.
When you’re ready to bake, weigh out the dough into roughly 50g balls, and place them onto a lined baking sheet, leaving about 8cm (3 inches) of space in between each dough-ball.
Bake the cookies in an oven preheated to 180°C for 7-8 minutes. Then, take the baking sheet out of the oven and bang in onto your tabletop several times. This will create that signature pan-banging creases on the edge of the cookie, but more importantly, it also causes the chocolate to pool up, which looks super nice! Return the cookies to the oven and bake for a further 8-10 minutes, or until the cookies are nicely browned at the edges. Repeat the pan-banging procedure every 2 minutes.
When the cookies have finished baking, remove from the oven and let it cool on the tray for 10 minutes, before transferring them onto a wire rack to further cool down.