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This over-the-top M&M's peanut butter cake brings playful peanut butter and bright chocolate candies into one stunning treat. You'll bite into fluffy peanut butter cake bits loaded with pop-of-color M&M's, all slathered in dreamy peanut butter frosting that'll thrill anyone who can't get enough of that combo.
Whipped this up for my nephew's birthday after he told me peanut butter and M&M's are his everything. The second he saw this, his face lit up. Now my family wants it anytime we all meet up.
Dreamy Ingredients
- M&M's: Adds crunch, color, and bites of chocolate everywhere
- Powdered sugar: Helps get a fluffy, smooth icing
- Heavy cream: Makes the frosting super easy to spread
- Vanilla extract: Rounds off all the flavors
- Large eggs: Make your cake richer and moist
- Granulated sugar: Sweetens things up and keeps the cake soft
- Creamy peanut butter: Gives you that classic nutty taste—go for supermarket classics for best results
- Unsalted butter: Makes things luscious and lets you pick how salty you want it
- Salt: Pops every flavor, especially the peanut butter
- Baking powder and baking soda: Work fast and slow together to give you the perfect lift
- All-purpose flour: Holds everything together but keeps it light
- Buttermilk: Adds a bit of tang and keeps the cake extra moist
Simple Step-by-Step
- Top It Off:
- Toss on extra M&M's to make it bright and festive. If you want, add some around the bottom edge for extra pop.
- Put It All Together:
- Plop the first cake layer on your plate and cover with frosting. Stack the second layer and coat the top and sides. Use a warmed spatula to get it all nice and smooth.
- Cut and Cool:
- Let the cakes chill in their pans for 10 minutes. Slide a knife around the edges, flip them out onto racks, and don’t touch until they’re fully cool. Take your time or they might break apart.
- Melt and Whip:
- Beat peanut butter and butter by themselves until light and seriously creamy, about 3 minutes. Slowly dump in powdered sugar bit by bit. Splash in heavy cream and vanilla, then whip it all fast for a few minutes—you want it fluffy!
- Bake On:
- Pour your batter into the pans and smooth the tops. Bake around 25–30 minutes, or until you poke a toothpick in and it comes out with just a couple moist bits.
- Add in M&M's:
- Fold your M&M's in real gently. Tumble them with just a sprinkle of flour first so they don't sink.
- Mix Together:
- Toss your dry mix into the peanut butter blend in three rounds, swapping in buttermilk between each bit. Go gently so you don’t over-stir, finish as soon as it all comes together.
- Add Eggs & Flavor:
- Crack eggs in one by one, beating after each so they disappear. Pour in vanilla and stir very briefly, just to mix—if you go too long, your cake gets tough.
- Cream It Up:
- Beat butter and peanut butter together until the texture is totally smooth, about 3 minutes. Drop in the sugar little by little and keep mixing until pale and fluffy, another few minutes.
- Mix the Dry Team:
- In a medium bowl, toss together flour, baking powder, baking soda, and salt until it all looks even and light.
- Get Set Up:
- Turn your oven to 350°F. Grease and flour two 9-inch cake pans—hit those corners well so nothing sticks.
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My grandma always said a peanut butter cake should taste like those beloved school lunch sandwiches—only way more fun. The first time I shared this with her, she actually said it's better than her old favorite and ended up sneaking a second piece after dinner.
Prep Ahead Hacks
This one’s super easy to make ahead. Bake off your cake layers a couple days early, let them cool, wrap in plastic, and just keep them out on the counter. The frosting is fine to make the day before—pop it in the fridge. When you’re ready, let it warm up a bit and give it a quick whip for easy spreading.
Allergy Swaps
If peanuts are a no-go, try almond or sunflower seed butter—almond gives a chill mild taste, sunflower keeps things nutty but safe. Swap the candy for whatever colorful treats fit your needs and keep an eye on sweetness since alternates aren’t as sugary as peanut butter.
Fun Serving Ideas
This goes awesome with a glass of cold milk or a scoop of vanilla ice cream. Want to go all out? Warm up some chocolate sauce and drizzle it over each slice right before serving. It's rich, so you don’t need huge pieces. Zap a slice for 10 seconds and your kitchen will smell amazing!
Baking Magic Explained
Using both baking soda and powder here is on purpose. The soda kicks in right away with buttermilk and the powder does its thing while baking. Double lift gives you a cake that’s fluffy but still solid. All that butter and peanut butter means you get a moist bite even days after it's made.
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Frequently Asked Questions
- → Is crunchy peanut butter okay to use?
Sure! Crunchy peanut butter adds texture if you like. For a smoother feel, stick with creamy peanut butter.
- → What kind of M&M's should I pick?
Classic chocolate M&M's work great, but you can try peanut or mini ones for extra flavor or crunch.
- → How do I keep the cake fresh?
It stays fresh up to 2 days at room temp in a sealed container, or refrigerate it for up to 5 days.
- → Can I change up the frosting?
Go for it! Cream cheese frosting or even chocolate ganache pairs wonderfully if you want a twist.
- → Can I prep the cake earlier?
Yep! You can bake the layers a day ahead. Just wrap them tight and frost right before serving for max freshness.
- → What works instead of buttermilk?
Mix 1/2 cup milk with 1/2 tablespoon lemon juice or vinegar. Let it sit 5 minutes, then use it like buttermilk.