Recipe: Peanut Brittle

The brittle you describe is made with baking soda. The sodium bicarbonate in the soda forms bubbles in the hot sugar mixture, which gives it the foamy texture you're looking for. Here's such a recipe, which I haven't tried. I hope it's a good one.

PEANUT BRITTLE

2 cups sugar
1 cup light corn syrup
1/2 cup hot water
2 cups raw Spanish peanuts
2 tbsp. butter
1/2 tsp. salt
2 tsp. vanilla
2 tsp. baking soda

Combine sugar, syrup, water in heavy pan. Boil to 230-240 degrees; add peanuts. Cook until amber-colored; continue cooking slowly to 300 degrees, stirring occasionally. Remove from heat and add butter, salt, vanilla and baking soda, stirring well. Pour immediately onto buttered cookie sheet. Cool and pull out until very thin (if desired). Break into pieces.