Preheat your oven to 350°F (175°C) and grease a 9x13 inch baking pan or line it with parchment paper.

In a large mixing bowl, cream the softened unsalted butter, light brown sugar, and granulated sugar until light and fluffy.

Add the eggs one at a time, mixing well after each addition, then add the vanilla extract until smooth.

Whisk together the flour, baking soda, and salt in a separate bowl.

Gradually add the dry ingredients to the wet mixture, mixing until just combined.

Fold in the butterscotch chips until evenly distributed.

Pour the batter into the prepared pan and spread evenly. Bake for 20-25 minutes until golden brown and a toothpick inserted comes out with moist crumbs.

Let cool completely on a wire rack before cutting into squares.