Honeycomb Candy — the bubbled, shattering sugar sweet

i. Origin & history

Honeycomb belongs to the old family of boiled sugar sweets made in home kitchens and at fairs across Britain and Ireland from the nineteenth century, once cheap refined sugar and bicarbonate of soda were both widely available. Because it needs nothing more than sugar, syrup and a spoonful of soda, it became a classic of bonfire night, fairgrounds and seaside sweet shops — hence the English name cinder toffee, for its resemblance to the clinker left in a fire grate.

Each English-speaking country kept its own name. Scots call it puff candy; in Northern Ireland a chewier, honeycombed relative called yellowman is sold at the Ould Lammas Fair in Ballycastle; New Zealanders call it hokey pokey, and hokey pokey ice cream — vanilla studded with small nuggets of honeycomb — is something of a national flavour there. In the United States it is sponge candy in Buffalo and western New York, often coated in chocolate, while in Wisconsin and Pennsylvania similar sweets go by sea foam or fairy food.

Commercial versions made honeycomb familiar worldwide. Fry's (later Cadbury's) Crunchie bar, a chocolate-coated honeycomb, dates from the late 1920s, and Australia's Violet Crumble is a similar bar with a longer history. If you remember buying honeycomb pieces without chocolate, you were most likely buying plain cinder toffee or 'honeycomb' sold loose by weight in sweet shops, often in irregular shards from a large slab.

Why 'honeycomb'? The set candy is full of irregular, waxy-looking cells that resemble a bee's comb. Honey is often added for flavour, but the name describes the structure, not the ingredients; many British recipes use only sugar and golden syrup. Korea's dalgona (or ppopgi) street candy is a thin cousin made with just sugar and a pinch of soda.

ii. How bicarbonate of soda makes the bubbles

Honeycomb is a chemistry trick performed in a saucepan. When sugar syrup is boiled, water evaporates and the temperature climbs; at around 149–154 °C (300–310 °F), the hard-crack stage, there is so little water left that the syrup will set glassy and brittle when it cools. At that temperature the syrup is also hot enough to break down bicarbonate of soda almost instantly.

Sodium bicarbonate decomposes in heat and reacts with the faintly acidic compounds in golden syrup and honey, releasing carbon dioxide. Stirred into hot caramel, it produces thousands of gas bubbles at once, and the mixture swells to three or four times its volume in a few seconds. Because the syrup is so concentrated, it begins setting around the bubbles almost as soon as they form, trapping them in a rigid sugar-glass foam.

Everything therefore comes down to timing and temperature. Too cool — below about 145 °C — and the candy contains too much water; it sets chewy and sticky and quickly turns soft. Too hot and the sugar burns, giving a bitter, dark candy. The soda must be whisked in quickly and evenly, for just a few seconds, then the foam poured out and left completely alone: every further stir or spread bursts bubbles and the candy sinks into a dense layer.

The amount of soda matters too. Too little and the foam is heavy; too much and the candy tastes soapy and metallic, with a brown, bitter edge. Roughly 1 teaspoon of bicarbonate for every 100 g of sugar is a reliable ratio, and sifting it first removes lumps that would otherwise leave pockets of bitter soda in the finished slab.

iii. Ingredients

Makes 20 servings · scroll the side panel to adjust

• 200 g caster or granulated sugar
• 70 g golden syrup or light corn syrup
• 30 g runny honey
• 2 tbsp water
• 2 tsp bicarbonate of soda (baking soda), sifted
• ¼ tsp fine salt
• 150 g dark or milk chocolate, optional, for dipping

Golden syrup (or corn syrup) is an invert sugar that stops the sucrose recrystallising into grainy fudge; it also contributes the acidity that helps the soda react. Honey adds flavour and colour, but it burns quickly — keep it to a small proportion, or replace it with more syrup for a cleaner caramel taste. Use bicarbonate of soda, not baking powder: baking powder contains its own acid and starch and gives a weaker, chalky foam. Check your soda is fresh, as old soda produces a flat candy. A little salt sharpens the toffee flavour. You will need a sugar thermometer; judging the stage by eye is possible but far less reliable.

iv. Method

1. Line a 20 cm square tin with baking paper, with the paper coming well up the sides. Sift the bicarbonate of soda into a small bowl and have a whisk and the tin right beside the stove.
2. Put the sugar, golden syrup, honey, water and salt in a deep, heavy saucepan — at least 3 litres, as the mixture will foam to several times its volume.
3. Heat gently, swirling the pan rather than stirring, until the sugar has fully dissolved and the syrup is clear, about 5 minutes.
4. Raise the heat and boil without stirring until the thermometer reads 150 °C (300 °F) and the syrup is a deep amber, like golden syrup held to the light — about 8–10 minutes. Watch closely towards the end; it colours fast.
5. Take the pan off the heat, tip in the bicarbonate and whisk vigorously for 3–5 seconds only, just until no streaks of soda remain. The mass will billow up immediately.
6. Pour straight into the tin in one go. Do not spread or smooth it — let it settle on its own.
7. Leave undisturbed at room temperature for at least 1 hour, until completely cold and hard. Lift out and break into pieces with the end of a rolling pin or a heavy knife.
8. To coat, dip the pieces in melted chocolate, set on baking paper and leave to firm, about 30 minutes.

v. Tips & common mistakes

• Hit hard crack. Below about 145 °C the candy sets chewy and goes sticky within hours. If you have no thermometer, a drop of syrup in cold water should snap cleanly, not bend.
• Use a deep pan. The foam rises dramatically and can overflow a small saucepan, which is dangerous with molten sugar.
• Whisk the soda for seconds, not minutes. Over-mixing bursts the bubbles and the candy collapses into a flat, dense sheet.
• Do not spread it in the tin. Pour once and walk away. Pressing or levelling the foam is the commonest reason for a heavy, sunken slab.
• Sift the soda and measure it. Lumps leave bitter spots, and too much gives a soapy, metallic aftertaste and a darker colour.
• Avoid humid days. Honeycomb is mostly sugar and absorbs moisture from the air; on a damp day the surface turns tacky quickly. Store it airtight as soon as it is cold.
• Clean the pan with hot water. Fill it with water and bring to the boil; the set sugar dissolves away without scrubbing.

vi. Variations

Chocolate-dipped honeycomb is the home version of the Crunchie or Violet Crumble; dark chocolate also protects the candy from moisture. Hokey pokey ice cream folds small chunks of honeycomb into vanilla ice cream, where they keep a crunchy, toffee-ish centre. Buffalo sponge candy is cooked for a finer, more melting texture and coated in milk or dark chocolate. Yellowman, from County Antrim, is chewier and pulled while warm. Crushed honeycomb is a good topping for ice cream, cheesecake or possets.

Other sugar candies that rely on careful boiling include sesame brittle, India's chikki and Iran's gaz nougat; for a softer confection, try toasted marshmallow fudge.

vii. Serving & storage

Serve honeycomb in rough shards as a sweet, with coffee, or crushed over ice cream, yoghurt or mousse. It is a traditional bonfire-night and Christmas treat in Britain, and makes an easy edible gift packed in cellophane or a tin. Break it just before serving for the cleanest pieces.

Store in an airtight container at cool room temperature, layered with baking paper, for up to 2 weeks; add a sachet of food-safe silica gel if you have one. Do not refrigerate it — the fridge is humid and the honeycomb will turn sticky and chewy. Chocolate-coated honeycomb keeps a little longer, around 3 weeks, because the chocolate seals out moisture. Honeycomb does not freeze well; condensation on thawing makes it weep.

ix. More from North American

• Toasted Marshmallow Fudge — smoky, creamy fudge
• Rum Balls — no-bake holiday truffles
• Sesame Brittle — glassy seed brittle
• Chikki — Indian peanut-jaggery brittle
• Gaz — Persian pistachio nougat
• Turkish Delight — rosewater lokum