If you're a foodie you probably saw that episode when Nigella Lawson makes a batch of sponge toffee as a hostess gift and by time she arrives at her guests house she must apologize for nibbling at the batch on the ride there in the taxi - it is quite funny!
I probably made my very first batch after seeing the episode, however it actually turned out pretty flat and brittle, it looks like the easiest recipe in the world considering how simple the steps and ingredients are so I knew it was something I needed to try again - someday.
I guess yesterday was the day, but to be honest my first batch actually messed up, so I'm going to warn you to keep a close eye on the candy thermometer, because I turned my head for just a second and I think the sugar over cooked resulting in a more "creme caramel" burned type sugar flavour in the toffee and it actually puffed up so much that it overflowed from the original pan and onto the counter top around it.
With my third batch I was very careful and made sure to keep a close eye on the temperature, gently whisk in the sifted baking soda while it was still on the stove and add the vanilla later on not early on in the recipe.
**My recipe called for 2 tbsp of baking soda, so I measured a rough estimate, the recipe below says 2 tsp so I'm not sure what the difference would be but you could give it a try and let me know.
I also used my new Presidents choice non stick baking pan that was on clearance at my local superstore, it is a glass pan that has a bubbly rough surface so I oiled a parchment well and placed it inside, and whatever corners touched the glass did not even stick, pretty cool!
Just another word of warning, if your kitchen is warm and the humidity is high in your home the toffee may begin to melt over time, so I would advise if you're making it as a gift to be careful and let it cool well in a colder dry place and package it at the last minute. I'm not sure this batch will melt but my first one did when I woke up in the morning, it had fused together like a big gooey mess even though the night before it looked very much like a normal sponge toffee regardless of the burnt taste.
2-1/2 cups (625 mL) granulated sugar
2/3 cup (150 mL) white corn syrup
1/3 cup (75 mL) water
4 tsp (18 mL) baking soda
2 tsp (10 mL) vanilla
Preparation In 12-cup (3 L) saucepan, stir together sugar, corn syrup and water over medium heat just until sugar dissolves.
Bring to boil; cook, without stirring but brushing down side of pan occasionally with pastry brush dipped in cold water, until candy thermometer reaches hard-crack stage of 300°F (149°C), or when 1 tsp (5 mL) hot syrup dropped into cold water forms hard brittle threads, about 10 minutes.
Remove from heat. Standing back and averting face, whisk in baking soda. (Caramel will bubble and sputter and increase in volume.) Whisk in vanilla.
Pour into greased foil-lined 13- x 9-inch (3.5 L) metal cake pan. Let cool in pan on rack without disturbing, about 2 hours. Break into 1-1/2-inch (4 cm) pieces. (Make-ahead: Store layered between waxed paper in airtight container for up to 1 month.) Source : Canadian Livng Holiday Cookbook: Fall 2009