Combine Sugar and Karo in saucepan. Stir thorouhgly. Add Peanuts. Cook to hardcrack on your candy thermometer. Stir while cooking. When mixture has cooked to hardcrack turn fire off. Add baking soda.

Quickly stir thoroughly. Pour out and spread onto buttered cookies sheet. Let sit till cold. Break into pieces and store in airtight container.

If you under cook, the Brittle will be sticky.