Rocky Road Ice Cream — American chocolate-marshmallow-almond ice cream

i. Origin & history

The flavour is generally dated to 1929, and there are two competing American claims. William Dreyer of Dreyer's in Oakland, California is said to have cut up marshmallows with his wife's sewing scissors and folded them into chocolate ice cream with walnuts, naming it after the stock market crash — the idea being to give people something to smile about while the road ahead was rocky. Fentons Creamery, also in Oakland, claims that its own George Farren developed a rocky road candy bar first and that Dreyer adapted it.

Both stories are Oakland stories from the same year, and they are not necessarily incompatible: a confection and an ice cream flavour of the same name emerging in the same city at the same moment is plausible. The Depression-era naming is the part that both accounts agree on and is the most interesting thing about it.

The composition then diverged by country, and this is a genuine and frequently confusing difference. In the United States, rocky road ice cream is chocolate ice cream with marshmallows and almonds — Dreyer's switched from walnuts to almonds early on. In Australia, rocky road is primarily a confection rather than an ice cream: a set slab of chocolate with marshmallows, coconut and often glacé cherries and peanuts. The British version follows the Australian model, usually adding broken biscuit.

So 'what is in rocky road' has different correct answers depending on where you are asking. The ice cream is American; the chocolate-and-marshmallow slab is Australian and British; and the cherry-and-coconut element that is standard in Australia is largely absent from the American ice cream.

ii. Keeping marshmallows soft at −18 °C

The technical problem in rocky road ice cream is that marshmallows freeze hard. A marshmallow is a foam of sugar syrup and gelatine, mostly air and water, and at freezer temperature that water freezes and the marshmallow becomes an unpleasant icy nugget.

There are three practical approaches. The first is to use mini marshmallows, which freeze hard too but are small enough that the texture reads as a chewy inclusion rather than a rock. The second is to cut larger marshmallows into small pieces and toss them in icing sugar, which keeps them separate and slightly drier. The third, and the best, is to make a marshmallow swirl — melting marshmallows with a little corn syrup into a ribbon that is folded through at the end. The added invert sugar depresses the freezing point enough that the ribbon stays soft and chewy straight from the freezer.

The base itself is a straightforward chocolate ice cream, and the usual rules apply: fat and sugar keep it scoopable, and both work by interfering with ice crystal formation. A chocolate base benefits from using both cocoa powder and melted chocolate — cocoa gives depth of flavour, melted chocolate gives body, and the cocoa butter in it also helps the texture.

The nuts need toasting, and this is not a refinement. Untoasted nuts in ice cream go soft and taste of very little; toasted nuts hold some crispness and their flavour survives being frozen. Toasting them and letting them cool completely before folding in also stops them melting the base.

Everything gets folded in at the end, after churning, when the base is the texture of soft-serve. Added earlier, the marshmallows and nuts interfere with the churn and end up unevenly distributed.

iii. Ingredients

Makes 8 servings · scroll the side panel to adjust

• 500 ml whole milk
• 500 ml double cream
• 200 g sugar
• 200 g dark chocolate, chopped
• 30 g cocoa
• 6 yolks
• Pinch salt
• 100 g mini marshmallows
• 100 g chocolate chips
• 100 g chopped almonds

Use both cocoa powder and dark chocolate in the base — cocoa for flavour depth, melted chocolate for body. Mini marshmallows are the easy route; for a swirl, ordinary marshmallows melted with a spoonful of corn syrup or glucose stay soft in the freezer where plain marshmallow does not. Almonds are the American standard, walnuts the original 1929 choice, and either should be toasted and cooled. Use double cream and whole milk; the fat is what keeps a home-churned ice cream from turning icy. A pinch of salt in a chocolate base is close to essential.

iv. Method

1. Warm milk, cream, half the sugar, chocolate and cocoa until chocolate melts.
2. Whisk yolks with remaining sugar and salt; temper; cook to 82 °C.
3. Strain. Chill 4 hours.
4. Churn until thick. Fold in marshmallows, chips and almonds.
5. Freeze 3 hours.

v. Tips & common mistakes

• Toast the nuts and cool them fully. Untoasted nuts go soft and flavourless in ice cream. Toasted ones keep some crispness. Let them cool completely before they go anywhere near the base.
• Make a marshmallow swirl rather than adding whole marshmallows. Melt marshmallows with a spoonful of corn syrup or glucose and ribbon it through at the end. The invert sugar lowers the freezing point so the swirl stays chewy instead of freezing into hard lumps.
• Chill the base thoroughly before churning. At least four hours, preferably overnight. A warm base churns slowly, incorporates less air and forms larger ice crystals — the main cause of grainy home-made ice cream.
• Fold the inclusions in after churning. When the base has the texture of soft-serve. Added before or during the churn, the marshmallows and nuts get pushed around unevenly and interfere with the aeration.
• Use a chilled container and press film onto the surface. A pre-frozen container stops the ice cream melting as you transfer it, and cling film pressed directly onto the surface prevents the ice crystals that form in the air gap.
• Let it soften before scooping. Five to ten minutes out of the freezer. Straight from −18 °C the chocolate base is rock-hard and the flavour is muted.

vi. Variations

Australian rocky road is a different thing entirely — a set chocolate confection with marshmallows, desiccated coconut, glacé cherries and often peanuts, cut into squares. The British version follows that model with broken biscuit added. Within the ice cream, common variations swap the nut — walnut was the 1929 original, almond the commercial standard, pecan a Southern US preference. Rocky road brownies, rocky road fudge and rocky road cookies all apply the same chocolate-marshmallow-nut combination to other formats.

vii. Serving & storage

Rocky road is scooped ice cream, served in bowls or cones, and it does not need adornment — it already contains its own texture and topping. If you want to push it, hot fudge sauce over it makes a sundae that is genuinely too much in an enjoyable way. Take it out of the freezer for five to ten minutes before serving, since a dense chocolate base is very hard when fully frozen and cold mutes the flavour considerably.

It keeps for up to two months in the freezer in an airtight container with cling film pressed onto the surface, though the marshmallows firm up over time and the nuts gradually soften. Home-made ice cream generally has a shorter useful life than commercial, which contains stabilisers — expect the best texture in the first two weeks. Never refreeze ice cream that has melted; the large ice crystals that form on the second freeze make it grainy and no amount of resting will fix it.

ix. More from North American

• Frozen Custard — Midwest soft-serve
• Hojicha Ice Cream — roasted-tea ice cream
• Durian Ice Cream — king-of-fruits ice cream
• Ube Ice Cream — Filipino purple yam
• Rainbow Sherbet — three-flavour scoop
• Baked Alaska — ice cream in meringue