Preheat oven to 375°F (190°C). Line baking sheets with parchment paper.
In a large bowl, cream together the sugars and butter until light and fluffy. Beat in the eggs one at a time, then stir in the vanilla.
In a separate bowl, whisk together the flour, baking soda, and salt. Gradually add to the wet ingredients, mixing until just combined. Stir in the butterscotch chips.
Drop by rounded tablespoons onto the prepared baking sheets. Bake for 10-12 minutes, or until the edges are golden brown.
Let cool on the baking sheets for a few minutes before transferring to a wire rack to cool completely.
Notes
Store cookies in an airtight container at room temperature for up to a week.