Whisk together the flour, baking soda, and salt. Set aside.
Using an electric mixer on medium speed, beat the cooled butter, brown sugar, and sugar until thoroughly combined. Mix in the eggs and vanilla.
Reduce mixer speed to low. Gradually add the flour mixture, mixing just until combined or a few small streaks of flour remain.
Stir the add-ins into the dough. If you like, reserve some of the add-ins for topping the cookies after they've baked.
Cover and chill the dough for 2 hours up to overnight.
Preheat the oven to 350°F (175°C). Line baking sheets with parchment paper or silicone liners.
Divide the dough into 3-tablespoon portions, roll into balls, and place on the prepared pans, leaving 2 inches between the cookies.
Bake one pan at a time for 14 to 16 minutes or until the cookies are golden brown. Take care not to over-bake.
Remove the pan from the oven and place on a wire rack. If you reserved any add-ins, press those on top of the warm cookies.
After the cookies have cooled on the pans for 5 minutes, transfer them from the pans directly onto a wire rack to cool completely.
Notes
You can use other add-ins; just keep the total amount around 5 cups. Try adding other flavor baking chips, caramel bits, crunchy cookie pieces, cereal, caramel bits, oats, chopped candy bars, dried fruits, or anything else you'd like.
Store in an airtight container at room temperature up to 5 days. Freeze unbaked cookie dough balls or baked and cooled cookies in a freezer-safe container up to 3 months.