In a large mixing bowl, combine the flour, salt, espresso, and baking soda. Whisk to combine.

In a stand mixer with the paddle attachment, add the brown and granulated sugars. Mix on low speed for one minute to combine.

Cut the butter into 8 pieces.

With the mixer on low speed, add the butter one piece at a time till coated fully.

On medium high speed, beat the butter and sugar until creamy. Scrape the side of the bowl as needed.

Reduce speed to low. Add the egg, scraping the side of the bowl to make sure it's fully mixed.

Add the vanilla, then the apple cider vinegar until just mixed.

Add the chocolate chips, mix for 15-30 seconds until the chips are coated.

Remove the mixing bowl, and fold the cookie dough to make sure the chips are evenly distributed.

Put in an airtight container, refrigerate for 24 hours.

Remove from refrigerator 1/2 hour before baking.

Preheat oven to 350º.

Using a medium ice cream scoop, place 6 balls of dough on a half-sheet baking pan lined with silpat or parchment. Roll each ball gently, then press slightly to compress the ball to the shape of a hockey puck.

Bake for 14-16 minutes, rotating halfway through.

Remove from oven, sprinkle slightly with the Malden flakes.

Let sit for 2 minutes on the baking pan, then remove to a cooling rack for 15 minutes.

Consume with milk or ice cream.

If there are any left, store in an airtight container. Refrigerating will extend their shelf life.