In a medium bowl, combine all dry ingredients (flour, cocoa powder, baking soda, and salt) mix together with a whisk or fork to combine and set aside
In the bowl of a stand-mixer fitted with a paddle attachment, add the butter, brown sugar and white sugar.
Mix together on medium speed for about 5 minutes, until mixture is light and fluffy, pausing halfway through to scrape the sides of the bowl with a nonstick spatula.
Add in the the espresso powder and the eggs r-the moisture from the eggs will help the granules dissolve. Mix again on medium speed, making sure to pause the mixer and scrape down the sides of the bowl again.
Add in the dry ingredients AND the chopped chocolate + chopped toffee and mix until thick dough forms. Adding these all together will help disperse the chocolate and toffee throughout the cookie!
Cover the dough with saran wrap and let it rest in the refrigerator for at least 1 hour
Scoop dough into 6 oz sized balls (alternatively, you can scoop into 4 oz size balls if you wish for a slightly smaller cookie)
Preheat the oven to 415 degrees and line two cookie sheets with parchment paper
Bake cookies, leaving at least 5 inches in between them, for 10 minutes. Top with extra pieces of chopped toffee and flakey salt!
