A Rich, Fudge-Frosted Sheet Cake for True Chocolate Lovers

If you’re all about chocolate, this Chocolate Overload Sheet Cake might be your new favorite. It’s rich, extra fudgy, and packed with mini chocolate chips, creamy cocoa frosting, and a border of Lindor truffles for good measure. This Chocolate Overload Sheet Cake starts with a cake mix but ends with bakery-level results—and it’s surprisingly easy to make at home.

Why You’ll Love This Recipe

• Starts with a cake mix for easy prep
• Extra rich and fudgy texture in every bite
• Chocolate overload from cake to frosting to toppings
• Topped with Lindor truffles for a bakery-style finish
• Perfect for parties, birthdays, or any chocolate craving
• Mini chocolate chips inside and out for double the fun
• Chocolate frosting is creamy, smooth, and pipes beautifully
• Kid-friendly but grown-up approved

Ingredient Notes

• Chocolate Cake Mix – Any standard 15.25 oz box works. I prefer Devil’s Food or Triple Chocolate for maximum richness.
• Buttermilk – Adds moisture and depth. If you don’t have it, mix 1 cup milk with 1 tablespoon lemon juice or vinegar and let it sit for 5–10 minutes.
• Sour Cream – Makes the cake extra moist and gives it a bakery-style texture. Full-fat is best here.
• Espresso Powder – Optional, but it deepens the chocolate flavor without making it taste like coffee.
• Mini Chocolate Chips – Stirred into the batter for extra chocolate in every bite. You can also sprinkle more on top.
• Salted Butter – Adds balance to the frosting and keeps it from being overly sweet.
• Lindor Truffles – These create a gorgeous and indulgent garnish. Stick with milk or dark chocolate for the best match.
• Heavy Cream – Helps the frosting whip up smooth and fluffy. Add a little at a time to reach your desired consistency.

Before You Bake

Do I need to chill the cake before frosting?
Yes. Chilling the cake for at least an hour helps the frosting set properly and makes it easier to spread without tearing the cake.

Can I leave out the espresso powder?
You can. It’s optional and only there to deepen the chocolate flavor—leaving it out won’t affect the texture or structure.

Can I use regular milk instead of buttermilk?
You can, but the texture won’t be quite as rich. For a quick substitute, mix 1 tablespoon lemon juice or vinegar into 1 cup of milk and let it sit for 5–10 minutes.

Chocolate Overload Sheet Cake

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• Author: Taryn Camp

Ingredients

Scale 1x2x3x

Cake

• 1 box chocolate cake mix
• 1/3 cup vegetable or canola oil
• 3 large eggs
• 1 cup buttermilk
• 1/2 cup sour cream
• 1 teaspoon vanilla extract
• 1 teaspoon espresso powder (optional, but boosts chocolate flavor)
• 1/2 teaspoon salt
• 1 cup mini chocolate chips

Frosting

• 1 cup butter, softened (I always use salted)
• 3 cups powdered sugar
• 1/2 cup cocoa powder
• 6–8 tablespoons heavy cream
• 1 teaspoon vanilla extract

Decorations

• Chocolate sprinkles
• Mini chocolate chips
• 6–8 Chocolate Lindor truffles

Tools

• Piping bags
• 1M piping tip
• 13 x 9-inch pan

Instructions

1. Preheat the oven to 350°F. Grease a 13 x 9-inch pan and line it with parchment paper.
2. In a large bowl, whisk together the cake mix, espresso powder, and salt.
3. Add oil, eggs, buttermilk, sour cream, and vanilla. Beat on medium speed for 2 minutes until smooth and creamy.
4. Fold in the mini chocolate chips, then pour the batter into the prepared pan.
5. Bake for 18–22 minutes, or until a toothpick inserted in the center comes out clean. Let the cake cool completely—refrigerate for about an hour for best results.
6. To make the frosting, beat butter for 2–3 minutes until fluffy. Add powdered sugar, cocoa powder, heavy cream, and vanilla. Adjust the cream until the frosting is thick but spreadable.
7. Spread about two-thirds of the frosting over the cooled cake.
8. Transfer the rest to a piping bag fitted with a 1M tip and pipe a border around the edges. Add Lindor truffles evenly spaced around the top.
9. Finish with a generous sprinkle of chocolate chips and chocolate sprinkles across the center.
10. Slice and serve. 

FAQ

What size pan should I use for a sheet cake?
A 13 x 9-inch pan is perfect for this recipe. Anything smaller could lead to overflow.

Can I use a different brand of chocolate cake mix?
Yes, any standard 15.25 oz chocolate cake mix works well—Devil’s Food and Triple Chocolate are top picks for richness.

How do I store chocolate overload sheet cake?
Cover and refrigerate for up to 5 days. Let it come to room temperature before serving for the best texture.

Can this sheet cake be frozen?
Yes. Freeze individual slices wrapped in plastic and foil for up to 2 months. Thaw overnight in the fridge.

Do I have to use Lindor truffles on top?
Nope! They’re for fun! You can swap them for chocolate chunks, chocolate bars, or leave them off entirely.

Sprinkle of Fun

There’s something so satisfying about showing up to a friend’s house with a dessert that steals the show—and this cake does exactly that. They’ve got dinner covered, so you get to be the one who brings the fun finale: a Chocolate Overload Sheet Cake piled high with frosting, truffles, and sprinkles. It’s casual, over-the-top, and guaranteed to get that “whoa, did you make this?!” moment.

Grab More Treats

• Chocolate lover? Check out Chocolate Buttercream Frosting
• So many more cake recipes, right here!
• Love sprinkles? You can find my Sprinkle-tastic ebook here