Ah, but you've gotten such good advice!
Sponge Candy is a bit of a fuss. Here is my recipe and method from my great-grandmother's cookbook (she a Confectioner of some notoriety in the Mother Land. Tried a myriad of times and highly true, but pick a day with humidity below 50% to make it, and the vinegar is an absolute necessity:
Sponge Candy
1 cup Golden Syrup
½ cup granulated sugar
1 teaspoon cider vinegar
1 tablespoon baking soda
Butter a 10-inch square pan and line the bottom and sides with parchment paper; butter the parchment paper and set the pan aside.
Combine the syrup, sugar and vinegar in a large, heavy pan and stir over medium heat until the sugar is completely dissolved and the mixture comes to a boil.
Clip a calibrated candy thermometer to the inside of the pan. Cook, without stirring, until the mixture reaches 300 degrees (F). Immediately remove the pan from the heat.
Sift the baking soda over the top of the hot mixture and very gently, very slowly stir. Be careful because the mixture will foam and rise.
Pour the still foaming syrup immediately into the prepared 10-inch pan. Do not spread the mixture – just let it settle naturally, or you will deflate the bubbles!
Allow the candy to cool completely. Remove from the pan and break into bite-sized pieces. Wrap each piece in waxed paper and store in an airtight container at room temperature for up to 1 week. Alternatively, dip in tempered chocolate
**I have also made a Maple-based version of this by reducing the Golden Syrup to ½ cup and adding ½ cup of Grade B Amber Maple Syrup with the vinegar.
