Line an 8x8-inch square pan with wax paper or parchment. Leave a little extra hanging over the edges to make it easy to lift the fudge out later.

Place the butterscotch baking chips in a microwave-safe glass bowl. Heat in 20–30 second intervals, stirring well after each round, until smooth and fully melted. Be careful not to overheat or the mixture can seize.

Stir the entire can of vanilla frosting into the melted chips. Mix until everything is fully combined and glossy.

Spread the mixture evenly into the prepared pan. Tap the pan gently on the counter to remove any air bubbles. Refrigerate for at least 1 hour, or until the fudge is firm enough to slice.

Use the parchment paper to lift the fudge from the pan, then cut into squares with a sharp knife.