Add the softened butter and vanilla to the bowl of a stand mixer fitted with the paddle attachment.
Mix on medium speed until the butter is smooth and creamy.
With the mixer on low, slowly add the flour and powdered sugar.
If the dough is too dry (if it doesn’t hold together when you squeeze it), add 1 tablespoon of milk at a time until the dough resembles a dry cookie dough. It shouldn’t be sticky, but just wet enough to hold together if you shape it into a ball.
Next, add the butterscotch chips and pecans and fold them into the cookie dough gently.
Shape the dough into a disc and wrap it in plastic wrap. Place it in the fridge to chill for 30 minutes.
While the dough chills, preheat your oven to 350°F and line two large baking sheets with parchment paper or silpat mats.
Once the dough has chilled, turn it out onto a lightly floured surface and roll it out to ¼” thick.
Cut out your desired shape (I used a 2” round cookie cutter) and transfer them to the parchment lined baking sheets.
Bake for 12-14 minutes or until the cookies are just starting to turn golden brown around the edges.
Allow the cookies to cool fully on the baking sheet. Then transfer any leftover cookies to an airtight container and store at room temperature for up to two days.