Preheat the oven to 350°F (175°C) and grease two 9-inch round cake pans.
In a large bowl, cream together the butter, brown sugar, and granulated sugar until light and fluffy.
Add eggs one at a time, mixing well after each addition.
In another bowl, whisk together flour, baking powder, baking soda, and salt.
Gradually add the dry ingredients to the wet mixture, alternating with buttermilk and stir in vanilla extract.
Divide the batter evenly between the prepared pans.
Bake for 30-35 minutes or until a toothpick comes out clean.
Allow cakes to cool in the pans for 10 minutes before transferring to wire racks.
Once cooled, frost with melted butterscotch chips mixed with whipped heavy cream.
Serve and enjoy your delicious butterscotch cake!