Mix Karo, Peanuts, Sugar, and Salt in a large microwaveable bowl.
Microwave and stir the mixture as follows…
(4)minutes, stir
(4)minutes, stir
(4)minutes, stir
(2)minute, stir
Add Vanilla and Butter and Stir.
Microwave 1 minute (keep in mind that the Peanut Brittle will be VERY HOT! Be sure to use pot holders and be very careful!
Add 2 Teaspoons of Baking Soda and stir quickly until the Peanut Brittle starts to foam.
Quickly pour the Peanut Brittle on to aluminum foil that has been sprayed with cooking spray. Tip: Put the aluminum foil on a baking sheet or something that will be able to withstand the heat.
Spread the Peanut Brittle as thin as possible and let the Peanut Brittle cool for 45 minute to an hour.
Break the Peanut Brittle apart into small pieces and enjoy!