Old Fashioned Chocolate Fudge Icing Recipe (Dairy-free!)

Few desserts feel as nostalgic as a cake topped with old-fashioned chocolate fudge icing. You may know it as “Old fashioned cooked fudge frosting” or “Grandmother’s fudge icing recipe.” This isn’t your everyday buttercream — it’s that smooth, glossy, candy-like layer that hardens ever so slightly as it cools, creating the perfect fudgy bite on top of a soft cake. It’s the kind of chocolate frosting that instantly transports you to family reunions, Sunday potlucks, or grandma’s kitchen.

And here’s the best part: this old-fashioned icing doesn’t require a drop of milk or cream. Instead, it uses simple pantry staples — margarine, cocoa powder, powdered sugar, and even some Coca Cola! The result is a dairy-free fudge icing with a deep chocolate flavor and a shiny finish that sets beautifully over sheet cakes.

​TIP: If you don’t need this to be dairy-free, go ahead and use unsalted butter with a pinch of salt, OR salted butter.

Why Coca Cola?

If you’ve ever tasted a classic Coca Cola cake from the South, you’ll know just how much magic that little bit of soda adds. It might sound unusual, but Coca Cola actually serves two important roles in this fudge icing:

• Liquid & texture: Instead of milk, Coke provides the liquid needed to bring the icing together. When boiled with butter and cocoa, it creates a silky base that blends seamlessly with powdered sugar.
• Flavor boost: The subtle caramel notes in the cola enhance the chocolate, giving the icing more depth and richness without tasting like soda.

It’s one of those old-fashioned tricks that’s been passed down for generations — and once you try it, you’ll understand why this chocolate fudge frosting is still a winner today!

What Makes This Icing “Old Fashioned”

Unlike whipped frostings that rely on air and structure from butter or shortening, this fudge icing is boiled on the stovetop. That simple step is what gives it its signature sheen and candy-like consistency.

The process goes like this:

1. Melt margarine with cocoa and Coca Cola in a medium saucepan over medium heat. I stir constantly with a wooden spoon. 
2. Bring it to a boil so the cocoa blooms and the mixture turns glossy, but remove it from the heat as soon as it comes to a full rolling boil.
3. Beat in powdered sugar with a whisk until it transforms into a smooth, pourable icing. (No need to transfer it to the bowl of a stand mixer – I just use a whisk right in the saucepan.)

Once you pour it over the entire cake, it spreads itself into a perfectly even layer, then sets into a rich fudge-like topping. It’s so easy and fuss-free…no need for a candy thermometer or boiling to the correct temperature or anything extra. You can’t really mess this one up, which is why it’s such a great recipe to choose to put on top of cakes.

Perfect Cakes for Fudge Icing

This icing really shines on simple cakes where the topping can be the star of the show. Some tried-and-true pairings include:

• Coca Cola Sheet Cake – The traditional pairing, where both cake and icing are infused with cola for a uniquely Southern flavor.
• Chocolate Zucchini Cake – Double up on the chocolate goodness with fudge icing over a soft cocoa cake.
• Vanilla or Yellow Cake – A lighter base that lets the glossy chocolate topping take center stage.
• Snack Cakes & Brownies – This icing adds just the right amount of extra sweetness and a smooth finish to a pan of brownies!

Because the icing sets firm enough to slice cleanly, it’s the perfect frosting for potlucks, bake sales, and gatherings where finger-friendly squares are needed. 

(Scroll to the end for the recipe card ⬇️)

Take note that the consistency of the frosting goes from pourable when hot, to set and touchable in just a short time. So spread it as soon as you pour it over the cake (or it will self-level) and not after it has set. 

Tips for Success

Working with boiled icings can feel a little different if you’re used to buttercreams, but the technique is simpler than it seems. Keep these tips in mind:

1. Don’t over-boil. Once the butter, cocoa, and Coke mixture comes to a rapid boil, it’s ready — there’s no need to keep cooking it.
2. Sift the powdered sugar. This step helps ensure your icing comes out silky smooth without lumps.
3. Pour while warm. The icing starts to set quickly, so spread it over your cake while it’s still glossy and pourable.
4. Work with a warm cake. Many bakers like to pour this icing directly over a just-baked cake. The slight warmth helps the icing spread evenly and soak in just a touch.

Why We Love This Dairy-Free Icing

There’s something about this old recipe for cooked fudge frosting that makes it unforgettable:

• Glossy finish: It looks shiny and beautiful without any extra effort.
• Fudge-like texture: It sets into a soft, sliceable topping that melts in your mouth, and it tastes like you’re eating homemade fudge!
• Deep chocolate flavor: Blooming the cocoa in butter and Coke intensifies its richness.
• Nostalgic appeal: This is the kind of icing that feels homemade in the best possible way.

It’s proof that sometimes the simplest, old fashioned family recipes are the ones that stand the test of time.

Variations to Try

Even with just four simple ingredients, you can play around with this icing to make it your own or take it to the next level. Here are a few ideas:

• Nutty Topping – Sprinkle chopped pecans or walnuts over the cake right after pouring the icing. They’ll stick as it sets, creating a crunchy layer.
• Mocha Twist – Stir in a teaspoon of instant coffee granules with the cocoa to deepen the chocolate flavor.
• Holiday Peppermint – Add a drop of peppermint extract, then sprinkle crushed candy canes on top for a festive look.
• Dark Chocolate Fudge Icing – Use Hershey’s dark cocoa powder for a richer, slightly less sweet version.

Our PEANUT BUTTER VERSION of this frosting is in ➡️ this post for Peanut Butter Sheet Cake!! ⬅️

This Chocolate Icing is actually the perfect complement to that peanut butter sheet cake if you’re a Reese’s lover!! My husband loves it for his birthday cake!

If chocolate desserts are your thing, I highly recommend pouring this delicious frosting over chocolate zucchini cake (add chocolate chips to the cake, too, and you’ve got an amazingly rich chocolate cake to serve up) or Coca Cola cake.

Honestly, this fudge frosting recipe is such a family favorite that we put it over SO many desserts. I love a couple of ganache recipes, too, but somehow this one always wins over those. 

Serving & Storing

• Best served fresh: This icing tastes incredible when freshly set.
• Room temperature storage: Keep the cake covered on the counter for up to 3 days.
• Refrigeration: You can refrigerate leftovers in an airtight container, but bring to room temperature before serving so the icing softens slightly. I’ve re-melted it for just a minute on the stove and it’s been successful.
• Freezer-friendly: A frosted cake freezes well when wrapped tightly; just thaw on the counter before serving.

A Naturally Dairy-Free Treat

One of the most unique aspects of this recipe is how naturally dairy-free it is. While many fudge icings rely on milk for liquid, this version uses Coca Cola instead — making it an easy choice for those avoiding dairy. The butter provides all the richness, and the end result is every bit as decadent as the traditional kind.

Old-fashioned chocolate fudge icing is one of those recipes that never goes out of style. With just four ingredients and a quick stovetop boil, you can create a glossy, fudge-like topping that transforms any cake into something special.

So next time you want a dessert that feels both nostalgic and indulgent, skip the buttercream and whip up a batch of this old-fashioned fudge icing. It’s a sweet reminder that the simplest recipes are often the best — and in this case, completely dairy-free, too.

Old Fashioned Chocolate Fudge Icing Recipe (Dairy-free!)

Prep Time: 2 minutes

Cook Time: 5 minutes

Total Time: 5 minutes

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Ingredients

• 1/2 cup margarine (1 stick)
• 1/4 cup unsweetened cocoa powder
• 1/3 cup Coca Cola
• 4 cups powdered sugar, sifted

Instructions

1. Melt margarine with cocoa and Coca Cola in a medium saucepan over medium heat and stir constantly.
2. Bring it to a boil so the cocoa blooms and the mixture turns glossy, but remove it from the heat as soon as it comes to a full rolling boil.
3. Beat in sifted powdered sugar with a whisk until it transforms into a smooth, pourable icing. (No need to transfer it to the bowl of a stand mixer – I just use a whisk right in the saucepan.)
4. Spread over hot cake so it levels itself, then leave it to cool until it's set.

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