Preheat oven to 350°F (175°C). Grease and flour three 8-inch round cake pans.

Whisk flour, baking powder, baking soda, and salt in a medium bowl.

In a large bowl, beat butter and brown sugar until fluffy. Add eggs one at a time, then mix in vanilla.

Mix in melted butterscotch chips.

Alternate adding dry ingredients with buttermilk and sour cream, beginning and ending with the dry.

Divide the batter evenly between prepared pans.

Bake for 25–30 minutes or until a toothpick comes out clean. Let cool completely.

While cakes cool, make the salted caramel sauce:

• Heat sugar in a saucepan over medium heat until melted and amber-colored.

• Stir in butter until melted.

• Slowly pour in cream while stirring. Cook for 1–2 minutes more, then stir in salt. Let cool.

Make the frosting: Beat butter until creamy, then add powdered sugar. Mix in caramel sauce, vanilla, and salt until smooth.

Assemble the cake: Layer with frosting between each layer, frost the outside, and drizzle with extra salted caramel.