Homemade Marshmallow Fluff
Homemade Marshmallow Fluff (Glossy + Stable + Not Too Sweet)
Light, fluffy homemade marshmallow fluff made with a cooked sugar syrup for a smooth, stable texture. Use it for frosting, fillings, fluffernutters, or the best (elevated) Rice Krispies treats.
- Candy Thermometer: The easiest way to measure your sugar temperature without guessing.
- Stand Mixer: Makes whipping hands-free and gives you the fluffiest result.
- Whisk Wiper: Helps scrape every last bit off your whisk. No fluff left behind.
Tip: The only “hard” part is pouring hot syrup. Go slow, aim between the bowl and whisk, and you’ll be golden.
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Ingredients
Marshmallow Fluff
- 1/3 cup water
- 3/4 cup granulated sugar
- 3/4 cup organic 100% pure blue agave (or honey)
- 3 large egg whites (room temperature)
- 1/2 tsp cream of tartar
- 1 tsp vanilla extract
Directions
Before You Start (Beginner-Friendly Setup)
- Make everything grease-free: Wipe down your mixing bowl, whisk attachment, and spatula with lemon juice or vinegar, then rinse and dry completely. Any grease can keep the egg whites from whipping.
- Separate eggs carefully: Even a tiny bit of yolk can ruin your volume. Separate one egg at a time into a small bowl, then add the white to the mixer bowl.
- Clip on your thermometer: If you’re using a candy thermometer, attach it now so the tip sits in the syrup without touching the bottom of the pan.
Cook the Sugar Syrup
- In a medium saucepan, gently stir together the water, sugar, and agave (or honey) just until combined.
- Turn heat to medium-high. Once it begins to heat, do not stir (stirring can cause the syrup to crystallize).
- Let the mixture boil until it reaches 240°F (soft-ball stage). This usually takes about 6–10 minutes depending on your stove.
- If you see sugar crystals on the sides of the pan: use a damp pastry brush to brush them down, or carefully swirl the pan (no aggressive stirring).
Whip the Egg Whites + Pour the Syrup
- While the syrup cooks, add egg whites and cream of tartar to the bowl of a stand mixer.
- When the syrup reaches about 225°F, start the mixer on medium-high and whip the egg whites to soft peaks (peaks hold but gently flop over).
- As soon as the syrup hits 240°F, remove it from heat immediately.
- With the mixer running on medium, very slowly pour the hot syrup into the egg whites in a thin, steady stream. Aim between the bowl and whisk — not directly onto the whisk (hot syrup flung everywhere is not fun).
Finish + Thicken
- Once all the syrup is added, increase the mixer to medium-high and whip for 7–8 minutes, until thick, glossy, and fluffy.
- Add vanilla extract and whip an additional 1–2 minutes.
- Your fluff is ready when it holds peaks, looks shiny, and feels light and airy (like frosting that belongs in a cartoon).
Sweetener Note: Agave keeps the fluff smooth and helps prevent crystallization. Honey works too, but the flavor will come through more.
Troubleshooting:
• My fluff is runny: Keep whipping. It thickens as it cools. If it’s still loose after 10–12 minutes, your syrup may have been under 240°F.
• My egg whites didn’t whip: Most common cause is grease or a bit of yolk. Wipe equipment well and separate eggs one at a time.
• My syrup crystallized/grainy: This happens if the syrup is stirred too much or crystals form on the pan sides. Brush down sides with water and avoid stirring once boiling.
Storage & Shelf Life
Store in an airtight container in the refrigerator.
Fridge: Up to 7 days.
Use Tip: Bring to room temperature and re-whip briefly (30–60 seconds) if it tightens up.
Freezing: Not recommended (texture gets weird after thawing).
How to Use It: Frosting, cupcake filling, fluffernutter sandwiches, s’mores dip, rice krispies treats, or swirled into buttercream.
Kid-Friendly Tip: Let kids help measure and watch the “fluff magic,” but keep them far away from the hot syrup step.
