Marshmallow Frosting + Cinnamon Buttercream

This recipe is Episode 4 of my 5-part Great Pumpkin Cake series.

Here’s everything in the lineup:

Episode 1 → Pumpkin Layer Cake
Episode 2 → No-Bake Pumpkin Cheesecake Filling
Episode 3 → Pumpkin Pudding Cookies
Episode 4 → Marshmallow Frosting + Cinnamon Buttercream (you’re here!)
Final Episode → Full Giant Pumpkin Cake Assembly

If you’re building your own fall cake combo, these two frostings are incredible as stand-alone recipes. The marshmallow frosting is glossy, torch-able, and cloud-soft — perfect for cupcakes, sheet cakes, s’mores cakes, or topping fall bars. The cinnamon buttercream is silky, warm, and cozy, and pairs beautifully with pumpkin, apple, pecan, and brown butter desserts.

Here are other recipes where you can use these frostings:

Cinnamon Buttercream → from my Apple Pie Layer Cake
Marshmallow Frosting → also used in my Pecan Pie Bars
Either frosting pairs beautifully with the Pumpkin Layer Cake (Episode 1)

Both of these complement the warm, cozy pumpkin flavors in the Great Pumpkin Cake perfectly.

Why You’ll Love These Frostings

Marshmallow Frosting

Torchable, glossy, cloud-like topping
No corn-syrup Italian method — this is simpler
Just 6 ingredients
Stays soft and silky for hours
Perfect for cupcakes, bars, and dramatic cake tops

Cinnamon Buttercream

Ultra-smooth and pipeable
Warm cinnamon flavor without being gritty
Not too sweet
Perfect for layer cakes or as your “dam + crumb coat” frosting
Amazing on cookies, sheet cakes, and fall bakes

Ingredient Highlights

Egg Whites — form the glossy meringue structure
Marshmallow Fluff — added after whipping for that bouncy marshmallow finish
Unsalted Butter — base for the smooth cinnamon buttercream
Cinnamon — adds warmth and cozy fall depth
Vanilla — enhances the marshmallow and buttercream flavor

Step Overview

Marshmallow Frosting

Heat egg whites + sugar to 160°F
Whip to stiff, glossy peaks
Add vanilla
Gently fold in warmed marshmallow fluff
Use immediately

Cinnamon Buttercream

Beat butter until pale and fluffy
Add sugar, cinnamon, vanilla, and salt
Whip until smooth and creamy
Use full batch for cakes or half batch for “dam + crumb coat”

These two frostings are the finishing touch that bring the Giant Pumpkin Cake to life, but they’re also the kind of recipes you’ll find yourself returning to all season long. The marshmallow frosting gives you that golden, toasted, cloud-soft finish, while the cinnamon buttercream adds warmth, structure, and the coziest fall flavor. Whether you’re using them for the full cake or swirling them onto cupcakes, bars, or simple weeknight bakes, they’re versatile, reliable, and truly delicious. I can’t wait to see how you use them — and how they come together in the final episode of the series.

Marshmallow Frosting + Cinnamon Buttercream (Episode 4: The Great Pumpkin Cake Series)

Two fall perfect frostings from Episode 4 of The Great Pumpkin Cake Series – a torchable marshmallow frosting and a silky cinnamon buttercream.

Print Recipe Pin Recipe

Prep Time 30

Cook Time 15

Total Time 45

Course: Dessert

Cuisine: American, Fall Baking

Ingredients Equipment Method Notes

Ingredients

Marshmallow Frosting

3 large egg whites
150 g ¾ cup granulated sugar
60 ml ¼ cup water
½ tsp cream of tartar optional
1 tsp vanilla extract
45 g about 3 Tbsp marshmallow fluff

Cinnamon Buttercream

225 g 1 cups unsalted butter, room temperature
150 g 1 ¼ cups powdered sugar, sifted
1 tsp vanilla extract or vanilla bean paste
1 ½ tsp ground cinnamon
Pinch of fine sea salt

Equipment

stand mixer or handheld mixer with whisk attachment
Heatproof mixing bowl
Saucepan for double boiler setup
Candy thermometer for heating egg whites to 160
Kitchen scale for accuracy
Rubber spatula
Piping bags + tips (optional)
Smalll offset spatula
Microwave safe bowl for warming marshmallow fluff 5-8 seconds
Small kitchen blow torch

Method

Marshmallow Frosting
Combine ingredients:
In a heatproof bowl, whisk together 3 large egg whites (≈ 90 g), 150 g (¾ cup) granulated sugar, 60 ml (¼ cup) water, and ½ tsp cream of tartar.
Heat to 160°F:
Set the bowl over a pot of gently simmering water. Whisk constantly until the sugar fully dissolves and the mixture reaches 160°F (71°C).
Whip to stiff peaks:
Transfer the mixture to a stand mixer fitted with the whisk attachment. Beat on high for 6–8 minutes until the meringue is thick, glossy, and holds stiff peaks.
Add vanilla:
Beat in 1 tsp vanilla extract for 5–10 seconds.
Loosen marshmallow fluff:
Microwave 45 g (about 3 Tbsp) marshmallow fluff for 5–8 seconds — just until slightly loosened (not hot).
Incorporate fluff carefully:
With the mixer on LOW, drizzle the warmed fluff in a thin ribbon over 5–10 seconds. Stop the mixer and finish folding by hand to avoid deflating the meringue.
Use immediately:
Best for piping, swooping, or torching.

Cinnamon Buttercream

Beat butter on medium-high 3–4 minutes until pale and fluffy.
Add powdered sugar, in increments fully mixing before each addition
Add cinnamon, vanilla, and salt. Mix on low until combined, then whip on high 2 minutes until smooth.

Notes

Tips & Tricks

When to Add Marshmallow Fluff

Always add fluff after the meringue reaches stiff peaks.

This prevents collapse, keeps the frosting pipeable, and maintains that glossy structure.

Avoid Over-Whipping

Once the fluff is added, stir gently. Whipping aggressively will loosen the frosting.

Perfect Buttercream Texture

Whip the butter long enough to drive out air bubbles and reduce graininess.

Double buttercream batch if you want to fully frost a layer cake

This is enough to frost a 8x8-inch sheet cake, but double if you want to fully frost any 6-inch layer cake in this frosting.