If you haven’t done so already, chop the chocolate bars and set aside.
Mix the granulated sugar, brown sugar, salt, espresso powder, and baking soda in a large bowl.
Measure our 2 ½ cups flour (spooned and leveled) and set aside.
In a smaller bowl, whisk together the 2 eggs and 2 tsp vanilla extracts, and set aside.
Pour the melted brown butter into the granulated sugar mixture and mix with a whisk or spatula until completely combined.
Add the 2/ ½ cups flour the butter and sugar mixture. Using a spatula, mix until there is no visible flour in the mixture, making sure to scrape the bottom of the bowl to incorporate everything.
Then, stir in the egg/vanilla mixture and continue mixing until combined.
At this point, you can take out the toffee from the freezer. If the toffee is too frozen to chop like you did the chocolate, you can break it into a few smaller pieces and add to a gallon ziplock bag. Seal the bag (you can also double bag the toffee as the toffee can break through the bag ). Hit the bagged toffee with a rolling pin until bite sized chunks form.
Add the toffee and the chopped chocolate to the cookie dough and thoroughly mix using a spatula or your hands.
Place a piece or parchment paper on a cookie sheet.
Once it’s mixed you can use a ¼ measuring cup or an ice cream scoop to measure out balls of dough onto the prepared cookie sheet. At this point, since we’re only resting the cookie dough, you can place them close together on the pan.
If the dough is still warm and spreads out when you try to form balls of dough, you can put the whole bowl in the fridge or freezer for 20 minutes to cool it down. This should help make it easier to form the cookies.
Cover the tray with plastic wrap, leaving a small corner uncovered to allow the cookies to dry out a bit.
Place the cookie tray in the fridge for 36-48 hours.
When you’re ready to bake, preheat the oven to 325 degrees.
Line multiple baking trays with parchment paper or silicone mats.
Place 4 to 6 cookies on the cookie sheet at least 2-3 inches apart from each other. These are big cookies that spread a lot!
Bake 18-20 minutes
Remove from oven and immediately sprinkle with sea salt (optional).
Let cool completely before trying to remove from the baking tray.