Maple Sponge Toffee
and a side order of science
My sweet tooth was aching today, so I decided to make sponge toffee. It’s one of the few candies that Rachel and our teenage kid actually enjoy, so I feel less guilty than I would if I was making a batch of sweets just for myself.
Digging up some old memories from over 20 years ago the last time I made sponge toffee, I recalled sugar syrup, vinegar and baking soda to make the bubbles. After researching, it turns out maple syrup is acidic enough to activate the soda without any added vinegar. Bonus!
Candy making is pure and simple science. The act of cooking gets the crystals to align together into a structure, but it won’t harden until it’s concentrated enough. Soft candy, with the consistency of fudge, is less than 95% sugar, while hard candies that have crunch are 99-100% sugar. How do you tell how pure sugar you have? Simple, you dissolve it in water, and boil it. The water will boil away over time and leave you with molten sugar.
As you heat the mixture, most of the energy from your stovetop will go towards the water phase change — that is, turning the water into vapour. As the vapour escapes, you’re left with more and more pure sugar. Once you get to 100% sugar (which will roughly happen at 300F), the mixture will begin to make caramel as the sugars start to brown, because there’s no easy path for the energy to dissipate as the water evaporates.
So, for the recipe, assemble your ingredients:
1c water
2.5c sugar
0.5c maple syrup (real maple syrup, made last spring by my in-laws)
2 tsp baking soda
Line a large baking pan with parchment paper. This makes a lot. I don’t recommend greasing a pan. Silicone works too. Non-stick and flexible is key.
Combine water, sugar and maple syrup in a large pot on high heat, and stir until dissolved.
Note: the pot I used was too small. Use one much larger than you think you need. My pot was about 1/4 full, and it still wasn’t enough space. The maple version foams like crazy, more than I remembered from the white-sugar-vinegar version.
Once the sugar is dissolved, do not stir any more. That just reincorporates cold and takes longer. You’ll have such an active boil that stirring is pretty unneccesary anyways.
Boil vigorously until it reaches 300F or hard crack stage. Hard crack means you can drizzle threads of it into a bowl of water, and it immediately hardens. Bending the threads have very little give and snap. Also, if it starts to smell like burning sugar, you’ve probably gone too far, to carmelization stage, and it’s done. Or you’ve spilled some sugar on the burner. Having a candy thermometer is way easier. I didn’t have that. I had an instant read thermometer that was too short. I eventually switched to the water-drop method.
Once it’s up to temperature, immediately remove it from the heat, and sprinkle the baking soda on top. Whisk it into the mix quickly and vigorously. If you’re not enthusiastic enough, you can have pockets of baking soda in your candy that didn’t react. You can even see one in the lead photo.
As it reacts to the acidity of the maple syrup, it’ll foam like mad. Pour it into your pan-paper mold, and resist the urge to spread it or touch it. Spreading it will just break the bubbles. Touching it will burn you.
Speaking of which, if you get molten sugar on you, DO NOT pour cold water on it. That will make the surface harden and the inside will continue to burn you. Better to run the hot water tap on it, and it’ll dissolve away with the least amount of pain.
Let the mixture cool completely, and then break it into easily-handled pieces.
When storing together in a container, dust with corn starch or cocoa. The pieces will pick up moisture from the air and glue themselves back together — which is why you often see sponge toffee sold as a single piece you break yourself, or smaller pieces coated in chocolate.
