These Key Lime Pie Marshmallows are a unique twist on the classic summer dessert. Light, fluffy, and bursting with bright citrus flavor, they’re finished with a graham cracker crumb coating for that nostalgic pie-like touch. Whether you’re gifting them or enjoying them as a treat, these homemade marshmallows bring zesty joy to every bite.

Why You’ll Love This Recipe

Tastes Like Key Lime Pie: The tart key lime juice and zest perfectly replicate the flavor of the iconic dessert in a soft, pillowy form.
Great for Gifting: Packaged in a cute box or bag, these marshmallows make a fun and thoughtful homemade gift.
Impressive Yet Simple: Even though they look gourmet, they’re surprisingly easy to make with just a few steps and basic tools.

Ingredients

(Tip: You’ll find the full list of ingredients and measurements in the recipe card below.)

For the Marshmallows:

3 envelopes unflavored gelatin
1/2 cup cold water (for blooming gelatin)
1 1/2 cups granulated sugar
1 cup light corn syrup
1/4 cup water
1/4 teaspoon salt
1/4 cup key lime juice
1 tablespoon key lime zest
1/2 teaspoon vanilla extract
Green food coloring (optional)

For the Coating:

1/2 cup powdered sugar
1/2 cup crushed graham crackers
2 tablespoons cornstarch

Directions

Prepare the Pan: Lightly grease a 9×13-inch baking pan and line it with parchment paper.
Bloom the Gelatin: In the bowl of a stand mixer, combine gelatin and 1/2 cup cold water. Let sit for 10 minutes.
Make the Syrup: In a saucepan, mix the sugar, corn syrup, and 1/4 cup water. Heat over medium until the sugar dissolves, then increase the heat and boil (without stirring) until it reaches 240°F (115°C) on a candy thermometer.
Combine with Gelatin: With the mixer on low, carefully pour the hot syrup into the gelatin. Increase to high speed and beat for 10–12 minutes until thick, white, and fluffy.
Flavor the Marshmallow: Add salt, key lime juice, zest, vanilla, and green food coloring (if using). Mix until just combined.
Set the Marshmallows: Pour into the prepared pan and smooth the top with a spatula. Let sit uncovered for at least 4 hours or overnight.
Make the Coating: Mix powdered sugar, crushed graham crackers, and cornstarch in a bowl.
Cut and Coat: Dust a cutting board with some coating. Turn out the marshmallow slab, peel off the parchment, and cut into squares. Toss in the coating mixture to prevent sticking.
Store: Keep marshmallows in an airtight container at room temperature.

Servings and Timing

Servings: 24 marshmallows
Prep Time: 30 minutes
Cook Time: 10 minutes
Total Time: 4 hours 40 minutes

Variations

Extra Tart: Add a bit more lime zest for a punchier citrus flavor.
Tropical Twist: Try adding a pinch of shredded coconut to the coating for a tropical flair.
Mini Marshmallows: Use a smaller pan for thicker marshmallows or cut into mini cubes for snacking or hot chocolate topping.

Storage/Reheating

Store marshmallows in an airtight container at room temperature for up to 1 week. Avoid refrigeration, as it can cause them to sweat and become sticky.

FAQs

Can I use bottled lime juice instead of fresh key lime juice?

Yes, but fresh key lime juice gives the best flavor. Bottled juice is a good alternative in a pinch.

How do I keep the marshmallows from sticking?

The coating of powdered sugar, graham crackers, and cornstarch prevents sticking. Be generous with the coating when cutting.

Do I need a candy thermometer?

Yes, for best results. The sugar syrup needs to reach 240°F (soft-ball stage) to create the right texture.

Can I use regular limes instead of key limes?

Yes, regular limes will work, though key limes have a more distinct, floral tang.

Can I make these vegan?

This recipe contains gelatin, which is not vegan. To make it vegan, try a plant-based gelatin substitute, though texture may vary.

Can I freeze marshmallows?

Freezing is not recommended, as it can alter the texture. Store at room temperature instead.

What type of mixer is best?

A stand mixer is ideal due to the mixing time, but a powerful hand mixer can work if used with care.

How long do these marshmallows last?

Up to one week in a cool, dry place in an airtight container.

Can I toast these marshmallows?

Yes, they toast beautifully just like classic marshmallows.

Are these suitable for kids to make?

The hot syrup step requires adult supervision, but kids can help with cutting and coating once the marshmallows are set.

Conclusion

Key Lime Pie Marshmallows are a playful and delicious treat that transforms a beloved pie flavor into a fluffy, snackable form. Easy to make and fun to gift, these citrusy, graham-coated confections bring a unique twist to homemade marshmallows. A must-try for key lime lovers and sweet treat fans alike!