From scratch · S’mores from scratch
Marshmallows
Soft vanilla marshmallows from gelatin, sugar and syrup, whipped, set in a pan and cut into squares.
✋ 37 min hands-on
⏱ 4 hr 49 min start to finish
🍽 About 40 marshmallows, 1½ inches square (a 9 × 13-inch pan).
Ingredients
- 3 package unflavored gelatin, unflavored, ¼-oz envelopes (about 2 tablespoons)
- 1 cup water, cold, divided
- 400 g granulated sugar
- ⅔ cup light corn syrup, or golden syrup
- 1½ g table salt
- 1 tbsp vanilla extract
- ¼ cup powdered sugar, for dusting
- ¼ cup cornstarch, for dusting
- 1 tsp vegetable oil (soybean), for the pan
Time
Hands-on time is when you’re busy; the rest is rising, simmering, chilling or cooling, when you can do something else.
| Step | Hands-on | Waiting |
|---|---|---|
| Bloom the gelatin and cook the syrup to 240°F | 10 min | 12 min |
| Whip | 12 min | – |
| Set in the pan | – | 4 hr |
| Cut and dust | 15 min | – |
| In all | 37 min | 4 hr 12 min |
How long it keeps
- Pantry: airtight, dusted, at room temperature. NDSU gives opened marshmallows about 1 month; homemade ones are softest in the first week or two.
Nutrition
Estimated from the ingredients’ USDA FoodData Central numbers.
Steps
You’ll need: 9 × 13-inch pan, stand mixer with whisk (or a strong hand mixer), heavy 3-quart saucepan, candy thermometer, oiled spatula, sharp knife or pizza cutter.
- Oil the pan lightly. Sift the powdered sugar and cornstarch together; dust the pan with about 2 tablespoons of the mix.
- Pour ½ cup of the cold water into the mixer bowl and sprinkle the gelatin over it. Let it soak (bloom) while you make the syrup.
- In the saucepan, stir the sugar, corn syrup, salt and the other ½ cup water over medium heat until the sugar dissolves. Clip on the thermometer and boil without stirring to 240°F (115°C), the soft-ball stage, about 10 to 12 minutes.
- Turn the mixer to low. Pour the hot syrup in a thin stream down the side of the bowl, away from the whisk, so it doesn’t spatter.
- Turn the mixer to high and whip 10 to 12 minutes, until the mixture is thick, white, glossy and just warm, and holds a ribbon. Whip in the vanilla for the last minute.
- Scrape it into the pan with the oiled spatula and smooth the top with an oiled hand or spatula. Dust the top.
- Leave it uncovered at room temperature at least 4 hours, or overnight, to set.
- Turn the slab out onto a board dusted with the sugar mix. Cut into 1½-inch squares with an oiled knife or pizza cutter, and toss the cut sides in the rest of the mix so they don’t stick.
⚖️ ScalingAn 8 × 8-inch pan takes half a batch (and gives thicker squares); the syrup still cooks to 240°F, a little faster. Small batches are hard to read on a thermometer, so use a small, deep pan.
🛡 SafetyHot sugar syrup is far hotter than boiling water and sticks to skin. Keep children back while it cooks and while you pour it, use a deep pan, and don’t taste it until it cools.
🛡 SafetyTest your candy thermometer first: in boiling water it should read 212°F at sea level. Above sea level, cook to 2°F less for every 1,000 feet (Colorado State University Extension).
Good to knowGolden syrup or light corn syrup both work; the syrup keeps the sugar from crystallizing.
Good to knowSome recipes cook the syrup a little higher, to 245 or 250°F, for a firmer marshmallow.
Good to knowFor toasting, cut them bigger (2 inches) and let them dry, uncovered, a few extra hours; drier marshmallows hold their shape over a fire.
📜 The old wayThe name comes from the marsh mallow plant: its root sap was once whipped with sugar into a soft candy. Gelatin took the root’s place in the late 1800s, and that is the marshmallow we know.
Sources
- Candy Making at High Elevation, Colorado State University Extension. Accessed 2026-10-25.
- Candy: Sugar Stages, Exploratorium, The Accidental Scientist: Science of Cooking. Accessed 2026-10-25.
- The Art of Candy Making, Utah State University Extension. Accessed 2026-10-25.
- Food Storage Guide (FN579), NDSU Extension, reviewed January 2023. Accessed 2026-10-25.
- Marshmallow, Grokipedia. Accessed 2026-10-25.