High Altitude Chocolate Peanut Butter Cake

If you love chocolate and peanut butter together, you’ll fall in love with this delicious high altitude chocolate peanut butter cake. Starting with my best, always perfect recipe for high altitude chocolate cake, I frosted it with fluffy peanut butter buttercream, flecked with chopped dark chocolate for texture and crunch. The soft, moist chocolate cake and the rich peanut butter frosting make the most incredible peanut butter and chocolate dessert you could imagine!

You might also love these flourless peanut butter chocolate chip cookies, s’mores chocolate chip cookie bars, and double Dutch dark chocolate ice cream.

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Why You’ll Love This Cake

Chocolate + Peanut Butter. These two ingredients are so perfectly complementary, with the rich, bittersweet chocolate, and creamy, salty peanut butter. This chocolate peanut butter cake is like eating the most incredible chocolate peanut butter cup but in a slice of cake!

Staple Pantry Ingredients. There’s nothing complicated about this recipe, and it uses ingredients that most bakers will already have on hand.

Soft, Creamy, Salty and Sweet. I love a good balance of flavors and textures in a cake, and this one has everything I could want.

High Altitude Tested. I develop all the recipes on my site for Denver’s altitude of 5,280 feet. If you’re at a lower or higher elevation, please see my FAQs for guidance on adjusting recipes for your altitude.

TIP: Make sure your ingredients, especially dairy products, are at room temperature for best results.

Ingredients

Cake

• Flour. For chocolate cakes, I like to use all-purpose flour. The flour gives a cake its structure and strength.
• Sugar. Granulated sugar adds sweetness and moisture.
• Cocoa Powder. Use a good-quality, unsweetened Dutch-processed cocoa powder for a rich chocolate flavor and deep, dark color.
• Baking Soda + Baking Powder. Leavens the cake so it rises.
• Salt. I always use coarse Kosher salt for baking and cooking. If using a finer table salt, you should use about half as much.
• Espresso Powder. The bitterness of espresso powder deepens and enhances the flavor of the chocolate, but does not make the cake taste like coffee. Be sure to use instant espresso powder or instant coffee. Regular coffee grounds are not suitable.
• Eggs. Gives the cake structure.
• Milk + Sour Cream. Use full-fat milk and sour cream for flavor, richness and moisture.
• Vegetable Oil. Adds moisture and lightness.
• Vanilla Extract. Flavor.

Buttercream

• Butter. Gives buttercream richness, moisture and flavor. I use unsalted butter, but you can use salted, and just omit the extra salt from the recipe.
• Powdered Sugar. Sweetens and thickens the frosting.
• Meringue Powder. Adds stability and improves texture.
• Salt. Balances the sweetness.
• Vanilla. Flavor.
• Milk. Thins the buttercream if it’s too stiff. Sometimes you’ll need to add it, and other times you won’t, as this will depend on your climate, and how hot or cold the weather is that day. During the warmer months, I almost never need to add the milk.
• Peanut Butter. Use a smooth, creamy peanut butter (not all-natural) to add delicious peanut butter flavor to the frosting.
• Chocolate. Chop a bar of good-quality chocolate to add to your buttercream, and you’ll love the texture and all the pretty flecks of chocolate.

See the recipe card at the end of the post for the full ingredients list and instructions.

Instructions

Bake the cakes.

• Preheat the oven to 350 F, and spray the bottoms of three 8-inch cake pans with non-stick spray.
• In a large bowl, sift together the flour, sugar, cocoa powder, espresso powder, baking soda, baking powder and salt.
• Separately, whisk together the eggs, milk, sour cream, oil and vanilla. Add the wet ingredients to the dry, and whisk until combined, about 15 seconds.
• Divide the batter between the pans. Bake on the center oven rack for about 22-28 minutes, until the tops of the cakes spring back when lightly touched, or a toothpick inserted in the center comes out clean.
• Set the pans on a cooling rack, cover loosely with a clean kitchen towel, and cool completely before frosting.

Make the buttercream.

• In the bowl of your stand mixer fitted with the whisk attachment, beat the butter on medium speed for 1 minute until smooth.
• With the mixer on low, gradually add the powdered sugar, meringue powder and salt, mixing to combine.
• Add the vanilla, and increase the speed to medium (#4-6 on a Kitchen Aid mixer); whip for 4-5 minutes until very light and fluffy, scraping the bowl down occasionally, and only adding the milk if needed for desired consistency. Turn the speed down to “stir” and mix for 2 minutes to eliminate big air bubbles.
• Add the peanut butter and fold in with a spatula until combined.

Frost and decorate your cake.

• Remove the cooled cakes from the pans. Place one cake layer on a cake board, and frost with a layer of buttercream. Repeat stacking and filling the cake layers, then frost all over with a thin “crumb coat” of buttercream. Refrigerate for 30 minutes to set the crumb coat, keeping the bowl of remaining buttercream covered.
• Add the chopped chocolate to the remaining buttercream. Frost all over with a final layer of buttercream.

Be sure to read all of my BAKING FAQs where I discuss ingredients, substitutions and common questions with cake making, so that you can be successful in your own baking! I also suggest reading these comprehensive posts on making Perfect American Buttercream, How to Stack, Fill, Crumb Coat and Frost Layer Cakes and How to Use Piping Bags.

Frequently Asked Questions

What’s the best cocoa powder for chocolate cake?

You should use a good-quality, unsweetened Dutch-processed cocoa powder. I always keep Drost and Rodelle on hand, and they both make wonderful chocolate cakes with a rich, dark chocolate flavor. King Arthur Baking Double Dutch Dark Cocoa is also excellent.

Is the cake soft and fluffy or dense and fudgy?

This is a very soft, moist and fluffy chocolate cake recipe.

Can I leave out the espresso powder?

The espresso powder enhances the flavor of the cocoa powder, but you can leave it out if you like.

Can I use natural peanut butter in the buttercream?

I don’t recommend it. Natural peanut butter just isn’t as stable as creamy peanut butter that contains other oils to stabilize the texture. Natural peanut butter might ruin the texture and consistency of your buttercream.

Why do you add meringue powder to the buttercream?

Meringue powder is a little known secret, with many uses other than just for royal icing. When you add a small amount to buttercream, it stabilizes the buttercream and improves its texture. You can find meringue powder on the baking aisle at your local craft stores, as well as at Walmart. You can leave it out, if you like, but it really does make a better buttercream.

If I have a peanut allergy, what can I use instead of peanut butter?

You can replace the peanut butter with any creamy nut butter, chocolate hazelnut spread or even Biscoff cookie butter.

Should I use chocolate chips or a chopped chocolate bar in the buttercream?

If you use chocolate chips, be sure to use the mini size. However, I prefer to finely chop a good-quality bar of chocolate. Chopping it yourself will give you very fine shards and chunks that look beautiful flecked throughout the peanut butter frosting.

Will this recipe work in a 9×13 pan?

Yes, you can bake the cake in a 9×13 pan, but you might need to bake it for a few minutes longer until a cake tester in the center comes out clean.

If I don’t have 8-inch cake pans, can I use 6-inch or 9-inch pans?

If you only have 9-inch pans, you can still make three layers of cake, but your layers will be thinner and the finished cake won’t be as tall, so you may want to multiply the recipe by 1 1/2 times to fill your pans better. For three 6-inch pans, cut the recipe in half.

Can I still bake this recipe if I don’t live at high altitude?

I test and develop all of my recipes for Denver’s high altitude of 5,280 feet. If you live at sea level or low altitude, you’ll need to make a few adjustments (such as increasing the leavening/decreasing the flour) for good results at your altitude. If you live at a higher altitude (more than 1,000 feet higher than Denver), then you will need to make some adjustments, too (such as decreasing the leavening/increasing the flour).

This is a great article with specific guidelines for adjusting recipe for various altitudes. Let me know if you have questions, and I’ll try to help!

What piping tip did you use for the swirls on top of the cake?

I used tip 6B. If you’re planning on piping swirls on the cake, be sure your chocolate is chopped very finely, as large chunks will clog the piping tip.

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