My mom made these when I was a kid. All the time. They're so easy and yummy. If you've never made them, give 'em a whirl:
1 c sugar
1 c light corn syrup
1 c peanut butter
6 c rice krispies
1/2 bag chocolate chips
1/2 bag butterscotch chips
In medium saucepan, mix the corn syrup and sugar. Over medium heat, heat to almost-boiling. I always take it off the burner as soon as it boils around the edges and I'm sure the sugar has dissolved (if it heats to a full rolling boil, your bars will be hard as a rock. Trust me.). Mix in the peanut butter until smooth and creamy.
Pour the peanut butter mixture over the rice krispies (I always cut the cereal by 1/2 a cup because I like mine extra chewy). Mix well. Press into greased 9x13" pan.
Melt chocolate and buttercotch chips in the microwave for 90 seconds (if they burn, it'll taste very bitter...check and stir every 30 seconds, as microwave speeds vary). Pour over scotcharoos and allow to firm up before serving.