Molasses Sponge Candy

Directions

1. 1.

   Line bottom and sides of a 13- by 9-inch baking pan with foil, then butter foil.

2. 2.

   Bring sugar, water, butter, and cream of tartar to a boil in a deep 3-quart heavy saucepan over moderate heat, stirring until sugar is dissolved, then wash down any sugar crystals with a pastry brush dipped in cold water. Boil without stirring until syrup registers 265°F (hard-ball stage) on a candy thermometer, about 10 minutes. Add molasses (don't stir) and continue to boil undisturbed until syrup registers 295°F (hard-crack stage), 4 to 5 minutes. Remove pan from heat and sift baking soda over syrup, then whisk to incorporate. (Use caution: mixture will bubble vigorously.)

3. 3.

   Immediately pour syrup into lined baking pan and cool completely. Lift candy in foil from pan, then discard foil and break candy into pieces.