Line a 9x5 inch loaf pan or an 8 inch square pan with nonstick foil.

Mix the cereal, pecans and butterscotch chips together and set aside.

In a 3 quart nonstick pan, melt the butter. Add the marshmallows and stir until they are melted, then stir in the peanut butter. Remove from heat and add the vanilla. Stir in the cereal mixture. Empty into pan and press down firmly. Chill the bars at room temperature for about half an hour. Lift from pan and score into 16 bars or squares.