1. Pour cereal into large, microwaveable bowl.
2. Melt butter in a saucepan with brown sugar, vanilla, Karo syrup and bring to a boil.
3. Boil for 30 seconds then remove from heat
4. Add baking soda, stirring quickly as the mixture will rise.
5. Pour mixture over cereal and stir.
6. Microwave for 1½ minutes, then stir and repeat microwaving three more times for 1½ minutes each time.
7. When finished microwaving stir in peanuts and pretzels.
8. Stir every 15 minutes until cool.
9. Once it is cool, add M&M's.
You can add raisins, dried cranberries, Cheerios, Reese's pieces etc. and change M&M's for different holidays/seasons.