In large heavy saucepan over low heat, melt butter.
Stir in sugar and corn syrup.
Cook over med. heat, stirring constantly, until sugar is dissolved and mixture is bubbly. Remove from heat.
Blend in peanut butter and vanilla.
Add cereals and peanuts, stirring until thoroughly coated.
Press firmly and evenly into buttered 9" square pan.
Chill until set (about 45 min.).
Cut into squares.
Store covered at room temperature.
Microwave directions: In large microwaveable bowl, microwave butter at high 30-60 seconds to melt. Mix in sugar and syrup. Microwave at high 2 1/2 minutes or until sugar is dissolved and mixture is bubbly, stirring 3 times. Follow steps 2 & 3.