Combine butter, sugar and brown sugar in a stand mixer on medium speed using the paddle attachment; cream until light and fluffy, 1-2 minutes.
Add the eggs and vanilla extract until fully combined, then sift together the flour, baking soda and salt and add it to the stand mixer until just combined.
Add in the butterscotch and milk chocolate chips until just combined then refrigerate batter for 30 minutes.
Using a rounded tablespoon, scoop the dough onto cookie sheets covered in parchment paper and bake 8-9 minutes or until slightly golden brown around the edges.
