Make the base cookie dough. In a large bowl, whisk together the brown sugar, granulated sugar, salt, and butter until a paste has combined with no lumps.
2. Step
Whisk in the egg and vanilla, beating until light ribbons fall off the whisk.
3. Step
Sift in the flour and baking soda, then fold the mixture with a spatula, being careful not to overmix. This will cause the gluten in the flour to toughen, which will result in cakier cookies.
4. Step
Divide the dough evenly between 6 medium bowls.
5. Step
Make chocolate chip cookie dough by adding the chocolate chips to the first bowl. Mix well and set aside.
6. Step
Make peanut butter cookie dough by adding the peanuts and peanut butter to the second bowl. Mix well and set aside.
7. Step
Make white chocolate macadamia nut cookie dough by adding the white chocolate chips and macadamia nuts to the third bowl. Mix well and set aside.
8. Step
Make chocolate candy cookie dough by adding chocolate candies to the fourth bowl. Mix well and set aside.
9. Step
Make double chocolate cookie dough by adding chocolate chips and cocoa powder to the fifth bowl. Mix well and set aside.
10. Step
Make caramel and pretzel cookie dough by adding chopped caramel and pretzels to the sixth bowl. Mix well and set aside.
11. Step
Line a 10-inch (30 cm) cast iron skillet with parchment paper. Make a triangular shape with the chocolate chip cookie dough and press into ⅙ of the pan. Repeat with the remaining doughs.
12. Step
Preheat the oven to 350°F (180°C).
13. Step
Chill the pan for at least 30 minutes, up to overnight.
14. Step
Bake the cookie for 30-45 minutes or stick a toothpick into the center of the cookie and the toothpick comes out clean
15. Step
Cool the cookie for 10-15 minutes before slicing and serving.
