Line an 8×8-inch pan with parchment paper and lightly grease it.

For the butterbeer layer, add butter, marshmallow crème, condensed milk, sugar, and caramel topping to a saucepan over medium-high heat.

Stir constantly until the mixture reaches a steady boil.

Once boiling, continue cooking for 4 minutes, stirring the entire time, until thickened and golden.

Remove from heat and stir in the butterscotch chips until completely melted and smooth.

Pour the mixture into the prepared pan and place it in the freezer briefly to partially set.

In a clean saucepan, combine butter, sugar, marshmallow crème, and condensed milk for the white chocolate layer.

Bring to a boil while stirring, then reduce heat slightly and cook for 2 minutes.

Remove from heat and stir in the white chocolate chips until smooth.

Pour the white chocolate layer evenly over the first layer.

Refrigerate for 2–3 hours (or freeze for about 1 hour) until fully firm.

Slice into small squares and serve.