Line a 9x9 inch baking pan with aluminum foil, ensuring it hangs over the edges for easy removal later. Lightly spray the foil with cooking spray.

Break graham crackers into pieces and arrange them snugly at the bottom of the prepared pan.

Evenly distribute mini marshmallows on top of the graham cracker base.

In a microwave-safe bowl, combine caramel bits and milk. Heat in 30-second intervals, stirring in between, until fully melted and smooth.

Drizzle the melted caramel evenly over the layer of marshmallows.

Sprinkle the chopped Butterfinger pieces generously over the caramel layer.

Melt the semi-sweet chocolate in the microwave, using 30-second bursts until smooth and melted.

Drizzle the melted chocolate over the Butterfinger layer.

Place the pan in the refrigerator and let the bars chill for about 1 hour, or until fully set and firm.

Once set, lift the bars from the pan using the overhanging foil edges and cut into squares or rectangles.