In a large heat proof bowl, place two sticks of butter and partially melt. Butter should be halfway or 80% melted and have visible chunks. Let butter cool to room temperature before adding sugars.
Chop chocolate, set aside.
In a large bowl, mix together flour, baking soda, and salt. Set aside.
Pour room temperature melted butter into large bowl with both sugars and whisk until combined.
Add eggs one at a time to butter mixture and mix until combined. Add and stir in vanilla.
Add dry ingredients to butter mixture and mix with a spatula until just combined. Once blended, add chopped chocolate, toasted peans, and chopped toffee bars.
Cover bowl with plastic wrap and chill for up to 1 hour or overnight.
Pre heat oven to 350 degrees. Line 2 baking sheets with parchment paper and set aside.
Scoop dough into balls (about 2 ½ tablespoons). If you have a food scale, dough should equal 1.7 ounces. Place 6 balls of dough onto the lined baking sheet, about two inches apart. Press 1/2 cup of chocolate chunks into dough if desired.
Bake one sheet at a time for 10 - 14 minutes. If choose to chill your dough overnight, cookies may take up to 14 minutes to bake due to the dough being colder. I found that when I only chilled my dough for an hour, cookies took 11 minutes to bake. Cookies are better when they are slightly underbaked. They should be slightly brown around the edges and slightly cracked and gooey in the middle.
Remove from the oven and let cookies sit on baking sheet for 3-5 minutes before transferring cookies to a wire rack to cool completely.
Store cookies in an airtight container at room temperature for up to five days.