01 -
Preheat the oven to 350°F and line 2 baking sheets with parchment paper.
02 -
In a large bowl, beat together the butter and sugars at medium speed using an electric mixer until smooth and well-combined with no visible butter chunks.
03 -
Add the egg and vanilla extract to the mixture, mixing on low speed until combined.
04 -
Add the flour, baking soda, and salt to the mixture. Mix until just incorporated. Avoid overmixing the dough.
05 -
Fold in the butterscotch chips, chocolate chips, and any additional add-ins, mixing only until evenly distributed. Do not overmix.
06 -
Using a small or large ice cream scoop or a heaping tablespoon, drop cookie dough portions onto the prepared baking sheets, spacing them 6 to 8 per pan, depending on size.
07 -
Gently press additional butterscotch and chocolate chips into the tops of the cookies before or after baking, if desired.
08 -
Bake one sheet at a time. For medium-sized cookies (2 tablespoons dough), bake 8-10 minutes. For large cookies (¼ cup dough), bake 10-13 minutes. Cookies are done when the bottoms and edges are lightly browned, and the tops feel firm when touched lightly.
09 -
Let the cookies cool on the baking sheets for 5 minutes, then transfer them to wire racks to cool completely. Sprinkle sea salt over the cookies while cooling.