Line a 9x13-inch baking pan with foil and spray the bottom and sides with baking spray. Set aside.

In a large pot on the stovetop, over medium heat, melt the butter. Once the butter has melted, add the mini marshmallows, reserving one cup of marshmallows for the last step. Stir the mixture occasionally and remove from the stovetop once the marshmallows are melted and the butter and marshmallows are incorporated.

Immediately stir in the butterscotch chips and stir until mostly melted. Stir in the salt and maple extract. Fold in the Rice Krispies cereal, cup by cup, gently. Once the cereal is completely incorporated, pour the mixture into the prepared pan and press out into an even layer.

Let cereal treats cool and set in the pan completely before cutting into desired sized squares.