Toasted Marshmallow Syrup

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This homemade toasted marshmallow syrup tastes like a toasted marshmallow melted right into your coffee. Made with sugar, water, toasted marshmallows, and vanilla, it’s an easy coffee syrup for lattes, iced coffee, cold brew, hot chocolate, and other homemade coffee drinks.

The trick to getting that real toasted marshmallow flavor is to brown the marshmallows before adding them to the syrup. The golden, caramelized edges add a subtle roasted flavor that you don’t get from plain marshmallows.

If you’re building an at-home coffee bar for a get-together, this is one of those coffee syrups that’s worth keeping in the fridge. Pair it with homemade peanut butter syrup to make something fantastic: a peanut butter marshmallow iced latte, inspired by the classic Fluffernutter combination.

What Is Toasted Marshmallow Syrup?

Toasted marshmallow syrup is a homemade simple syrup flavored with toasted marshmallows and vanilla. The sugar and water create the syrup base, while the melted marshmallows add their sweet, creamy flavor.

Toasting the marshmallows first gives this syrup a deeper flavor with lightly browned, caramelized notes.

Ingredients

See the recipe card for exact amounts.

• Granulated sugar: creates the sweet syrup base with water. Regular white granulated sugar dissolves easily and gives the syrup its sweetness.
• Large marshmallows: Large marshmallows are toasted until golden brown, then melted into the sugar syrup. I use 8 large marshmallows for a noticeable marshmallow flavor without making the syrup excessively thick.
• Vanilla: Vanilla adds another layer of flavor and makes the marshmallow taste more pronounced. Vanilla bean paste works especially well, but vanilla extract is fine too.

Tips for Making Marshmallow Simple Syrup

• Toast the marshmallows well. The browned exterior is what gives this syrup its toasted flavor.
• Don’t walk away from the saucepan. The marshmallow mixture can foam and rise quickly.
• Use a fine-mesh sieve. A few small pieces of toasted marshmallow may remain after melting.
• Cool before refrigerating. Allow the syrup to cool completely before sealing the container.

How to Toast Marshmallows for Syrup

You can toast the marshmallows using an air fryer, an oven broiler, a kitchen torch, or a good old campfire if available.

For this recipe, you want plenty of golden-brown color with some darker toasted spots. They don’t need to be completely black.

Air fryer: Place the marshmallows in the air fryer and toast for about 4 minutes, watching them closely.

Oven broiler: Arrange the marshmallows on a baking sheet lined with a silicone baking mat and broil until browned. Stay nearby because marshmallows can burn very quickly. Don’t use parchment paper, which can catch fire under the broiler.

Kitchen torch: Toast the outside of each marshmallow with a kitchen torch until browned.

The more browned surface you get, the more noticeable the toasted flavor will be.

How to Make Toasted Marshmallow Syrup

1. Toast 8 large marshmallows until golden brown with some darker spots. Set aside.

2. Add the sugar and water to a medium saucepan. Heat over medium-high heat, whisking often, for about 5 minutes, until the sugar has completely dissolved and the mixture comes to a boil.
3. Add the toasted marshmallows and reduce the heat to medium. Whisk constantly for 2–3 minutes, until the marshmallows have melted into the syrup.
4. Control the foam. The marshmallows will cause the syrup to foam considerably as they melt. Keep whisking and lower the heat if necessary. If the foam rises quickly, briefly lift the saucepan from the burner until it settles.
5. Pour the syrup through a fine-mesh sieve into a clean jar or container. This removes any small pieces of marshmallow that haven’t completely dissolved.
6. Stir in the vanilla bean paste or vanilla extract.
7. Let the syrup cool completely before covering and storing it in the refrigerator.

Why Does Marshmallow Syrup Foam?

Marshmallows contain gelatin and air. Heating can cause the air bubbles to expand, making the syrup foam.

This is normal, but the foam can rise quickly and cause the syrup to boil over. Keep the saucepan on the stove while the marshmallows melt, and reduce the heat if needed.

If the foam gets too high, lift the pan off the heat for a few seconds. Once it settles, return it to the burner and continue cooking.

How to Use Toasted Marshmallow Syrup

Use toasted marshmallow syrup anywhere you’d use a sweet coffee syrup.

Try it in:

• Iced lattes
• Hot lattes
• Iced coffee
• Espresso drinks
• Hot chocolate
• Milkshakes

For coffee, start with 1–2 tablespoons per serving and adjust the sweetness to your taste.

Toasted Marshmallow Latte

Add toasted marshmallow syrup to a latte made with espresso and steamed milk. For an iced version, combine espresso, milk, and syrup, then pour over ice.

Peanut Butter Marshmallow Iced Latte

One of my favorite ways to use this syrup is in a peanut butter marshmallow iced latte. The combination is inspired by a classic Fluffernutter, pairing sweet marshmallow with nutty peanut butter.

Storage

Store toasted marshmallow syrup in a clean, airtight jar or bottle in the refrigerator for a week or two.

The syrup may become thicker when it’s cold. Let it sit at room temperature briefly and stir before using if needed.

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