Toasted Marshmallow Fudge — smoky campfire flavour in a chocolate slab

i. Origin & history

Fudge is an American invention of the late nineteenth century. The best-known early account comes from a student at Vassar College in New York, who wrote that she had made fudge there in the late 1880s from a recipe a classmate had got in Baltimore; women's colleges soon made batches of fudge a dormitory tradition. The name may come from the old verb 'to fudge', meaning to botch or fake — a nod to a failed batch of caramels, according to one popular story. Classic fudge is cooked sugar, milk and butter, boiled to the soft-ball stage and beaten as it cools so it sets into tiny sugar crystals.

Marshmallows entered fudge in the twentieth century. Once marshmallows and jarred marshmallow creme were mass-produced, home cooks discovered that stirring them into hot fudge made it smoother, softer and far more forgiving; marshmallow-based 'fantasy fudge' recipes became famous on American product labels from the mid-century.

The flavour of toasted marshmallow belongs to the s'more: a toasted marshmallow and a square of chocolate pressed between graham crackers, eaten around a campfire. A recipe for 'Some Mores' appeared in a 1927 Girl Scouts handbook, and the s'more has been a symbol of American summer camping ever since. In the 2010s s'mores flavour became a broad trend — in cupcakes, ice cream, brownies and coffee drinks — helped by home blowtorches, which let anyone toast marshmallows indoors.

Toasted marshmallow fudge comes out of that trend. It has no single inventor; it is a modern home-baking and gift-shop sweet, often sold as s'mores fudge with graham-cracker pieces folded in, and it sits comfortably beside other American confections such as seven layer bars and rocky road.

ii. Toasting marshmallows twice, and a fudge that cannot fail

This is a condensed-milk fudge, which works quite differently from traditional cooked fudge. Classic fudge depends on controlling sugar crystallisation: boil to 112–115 °C, cool, then beat at the right moment, or it turns grainy or never sets. Here the sugar is already dissolved in the condensed milk, and it is the cocoa butter in the chocolate that sets the fudge as it cools — the same principle as a ganache, but much firmer. There is no thermometer and almost nothing to go wrong, provided the chocolate is melted gently.

The flavour comes from the marshmallows. A marshmallow is a foam of sugar syrup set with gelatin. When toasted, the sugar on its surface caramelises and the small amount of protein undergoes Maillard browning, producing the nutty, smoky, slightly bitter notes that define a campfire marshmallow. Plain, untoasted marshmallows stirred into fudge add sweetness and chew, but not that flavour.

So the marshmallows are toasted twice. Half are browned under a hot grill and folded into the warm fudge, where they partly melt into smoky ribbons. The other half are pressed onto the surface and torched just before serving, for the visual effect and a fresh, crisp caramel crust.

Timing matters for the topping. A torched marshmallow is crisp only for an hour or so; in the fridge it absorbs moisture, turns sticky and the toasted crust softens. That is why the top is torched after the fudge has set and shortly before it is cut and served.

iii. Ingredients

Makes 36 servings · scroll the side panel to adjust

• 150 g mini marshmallows, divided
• 300 g dark chocolate (50–60%), chopped
• 100 g milk chocolate, chopped
• 397 g tin sweetened condensed milk
• 30 g unsalted butter
• 1 tsp vanilla extract
• ¼ tsp fine salt
• 60 g graham crackers or digestive biscuits, broken into small pieces, optional

A mix of dark and milk chocolate gives a fudge that tastes rich but not bitter, and sets firm yet creamy; all dark chocolate gives a firmer, more intense slab. Avoid chocolate chips, which contain stabilisers that can make the fudge stiff. Mini marshmallows toast evenly and spread neatly over the top; large marshmallows can be snipped into quarters with oiled scissors. Standard marshmallows contain gelatin; for a vegetarian fudge, use gelatin-free marshmallows, which toast just as well. The salt matters more than it seems — it cuts the sweetness of the condensed milk.

iv. Method

1. Line a 20 cm square tin with baking paper, leaving an overhang. Heat the grill to high and line a baking tray with lightly oiled foil.
2. Spread 75 g of the marshmallows on the tray in a single layer. Grill for 1–2 minutes, watching constantly, until puffed and deep golden brown. Leave to cool for 5 minutes, then scrape them off the foil.
3. Put both chocolates, the condensed milk and the butter in a heavy saucepan over low heat. Stir constantly with a spatula until just melted and smooth, about 5 minutes; do not let it bubble.
4. Take the pan off the heat and stir in the vanilla and salt. Leave for 2 minutes, then fold in the toasted marshmallows and the biscuit pieces, if using, with just a few strokes so the marshmallow stays in ribbons.
5. Scrape into the tin and level the top. Press the remaining 75 g of marshmallows lightly into the surface while the fudge is still warm.
6. Cool for 30 minutes, then refrigerate for at least 3 hours, until firm.
7. Lift the fudge out of the tin. Just before serving, run a kitchen blowtorch over the marshmallows until golden and lightly charred in places.
8. Cut into 36 squares with a large knife dipped in hot water and wiped dry between each cut.

v. Tips & common mistakes

• Melt over low heat. Chocolate and condensed milk scorch easily. Overheated fudge turns grainy and oily; stir constantly and stop as soon as it is smooth.
• Do not walk away from the grill. Marshmallows go from golden to burnt in seconds. Stay by the oven door.
• Cool the fudge slightly before folding. If it is very hot, the toasted marshmallows dissolve completely; a short rest keeps them in visible swirls.
• Torch at the last minute. Toasted marshmallows soften and weep in the fridge. Torch just before serving for a crisp, glossy top.
• Cut with a hot knife. Marshmallow drags and sticks; a knife dipped in hot water slices cleanly through both fudge and topping.
• Use real chocolate. Bars rather than chips, and decent quality. With so few ingredients, the chocolate is the flavour.

vi. Variations

S'mores fudge folds in graham-cracker pieces and adds a crumb layer on the base of the tin. White chocolate toasted marshmallow fudge uses 400 g white chocolate and a pinch more salt; it is very sweet but pretty, with golden marshmallows on ivory fudge. Rocky road fudge adds toasted almonds or peanuts. Salted caramel versions swirl 3 tbsp thick caramel through the top. Espresso fudge adds 2 tsp instant espresso powder to the melting chocolate, which deepens the toasted notes.

For other American confections, see crackly honeycomb candy, boozy rum balls and condensed-milk seven layer bars. From further afield, the Italian chocolate salami and the marshmallow-filled Choco Pie are close relatives in spirit.

vii. Serving & storage

Serve in small squares — the fudge is rich — at room temperature, when it is soft and creamy, with coffee or hot chocolate. Toasted marshmallow fudge makes a good gift, packed in a tin between sheets of baking paper; for gifts, toast the top just before packing, or leave the marshmallows untoasted and give it with instructions to torch.

Store in an airtight container in the fridge for up to 1 week, or at cool room temperature for 3–4 days; the toasted top softens over time, so re-torch briefly before serving if you like. The fudge freezes well without its topping for up to 3 months: freeze the plain slab, thaw in the fridge overnight, then press on marshmallows and torch.

ix. More from North American

• Seven Layer Bars — coconut and chocolate magic bars
• Rum Balls — no-bake holiday truffles
• Honeycomb Candy — shattering sugar foam
• Rocky Road Ice Cream — chocolate, marshmallow and nuts
• Choco Pie — marshmallow-filled chocolate cake
• Chocolate Salami — Italian no-bake log