Behold the Peanut Brittle Fudge Cake!
Peanut butter cake layers with a new easy recipe for peanut butter fudge filling
of course no peanut butter cake is complete without peanut butter buttercream!

Peanut Brittle Fudge Cake is quite the grand project
but the results are well worth the effort!

When using flax meal as the egg replacer the moistness that is added to the cake is just unmatched!

Oh by the way, if you’re just here for the Peanut Brittle ~ I’ve got that too!

Not sponsored by any product or company below
Notes for Success:
IN THE VIDEO WHERE I SAID HARD CRACK STAGE FOR PEANUT BRITTLE IS 270°F – THE CORRECT TEMPERATURE TO COOK IT IS 300°F
You will need a candy thermometer to get to the correct temperature
A total of four recipes are needed to make this entire cake, but they can all be made ahead of time. The cake can be baked the day before, wrapped and refrigerated until needed
Ganache can be made up to a week ahead, and the same goes for the peanut butter fudge filling!
If you are like me you always have buttercream stashed away in the refrigerator but if not, that can also be made up to a week ahead!
Additionally using Peanut Butter Powder to make peanut butter buttercream is a really awesome hack! Less fat and super intense peanut butter flavor!
Then when you are ready to build the cake just follow along in the video below!


Peanut Brittle Fudge Cake
Ingredients
For the Peanut Butter Cake
- 18 Tbs Vegan Butter 255g
- 2¼ cups Granulated Sugar 450g
- 1 cup Creamy Peanut Butter 240g
- 5 Tbs Flax Meal 40g
- ¾ cup Warm Water 180ml
- 2 teaspoons Vanilla Extract 10ml
- ¾ cup Plant Milk 180ml
- 1 Tbs Vinegar 15ml
- 2½ cups All Purpose Flour 312g
- 1¼ teaspoons Baking Powder
For the Peanut Butter Fudge:
- 1 cup Peanut Butter 1 cup 240g
- 1½ cups Corn Syrup or Agave 355ml
- ¼ cup Coconut Oil 56g
- 1 teaspoon Vanilla Extract 5ml
For the Peanut Brittle:
- 1 cup Granulated Sugar 200g
- ½ cup Corn Syrup 120ml
- ¼ cup Water 60ml
- 2 Tbs Vegan Butter 28g
- 1 teaspoon Baking Soda
- 1 cup Unsalted Raw Peanuts 150g
For the Icings
- 1 Recipe Peanut Butter Buttercream
- ½ Recipe Fudge Icing
- ¼ Recipe Ganache
Instructions
- Preheat the oven to 350°F & grease and parchment line 4-7" cake pans (2-8" pans will also work)
- Combine the flax meal with the warm water & set aside to thicken about 5 minutes.
- Sift the baking powder with the flour set aside
- Combine the vinegar & vanilla extract with the plant milk
- With the paddle attachment on your electric mixer cream the room temperature vegan butter with the sugar on medium to high speed until fluffy about 3-5 minutes then add the peanut butter to blend well
- Add the flax paste & whip on high speed to emulsify for 10 seconds
- While mixing on low speed add about 1/3 of the flour mixture, mix just until it is incorporated then while still mixing on low speed slowly add in about half of the milk mixture
- Quickly add another 1/3 of the flour mixing just until it is incorporated then add the rest of the milk mixture & finishing with the last addition of flour. This is called alternating creaming method & the entire process should not take more than 1 minute
- Divide evenly between the prepared pans & bake for approximately 25-30 minutes or when they are springy to the touch when you gently press the centers
- For the Peanut Butter Fudge:Combine the peanut butter and agave or corn syrup in a heavy bottom sauce pot and bring to a boil stirring constantly.
- Boil for about 1 minute then add the coconut oil and vanilla extract and transfer to a bowl to cool
- While the cakes are baking and/or cooling prepare the buttercream & ganache recipes
- For the Peanut Brittle: Combine the sugar, corn syrup & water in a medium sized heavy sauce pot & bring to a boil stirring occasionally with a wooden spoon or a heat proof silicone spatula to dissolve the sugar but do not stir it after it comes to a boil .
- Once it boils, Insert a candy thermometer & continue to boil without stirring until it is 300-309°F (*See notes above about my speaking error in the video) it should just start to turn golden brown, then add the vegan butter, baking soda, vanilla extract and peanuts, stirring well to combine
- Spread mixture on a lightly oiled sheet pan or a silicone baking mat & let it cool completely then crack it up to jagged pieces
- Assemble cake as shown in the video
Video
Notes

This has to go down as one of your most amazing creations. Looks delicious – and dangerous. How can you eat just one slice? That’s why I’ll make the cupcakes.
I just bought flax seeds to try your recipes. Is it still okay to put the flax seed in the coffee grinder to make my own flax meal?
yes that is the best way to do it if you are not using them quickly, since they have a high Omega 3 fat count, they can go rancid quick, so store them in the freezer and grind them as you need.
Hi Gretchen. I have been following you since the beginning. I love your recipes. I am not vegan. I would like to know if I make these recipes and I use butter eggs buttermilk etc as substitutes will the products come out ok. Thanks for everything.
thanks! Yes you can use cow dairy for everything I use plant based, and the eggs.. Hmm I say do 2 (Just be aware that as I stated in the video this recipe really does benefit from the flax, and that is why I recommend to use it instead of eggs – of course aside from the vegan aspect, it just really is better with flax)
Great PB cake recipe, my layers came out quite flat though and I’m not sure what i did wrong! The PB fudge is amazing! Thanks Gretchen!
Hi, I’m a little confused on the peanut brittle. The recipe states 60ml water and 120ml corn syrup, but the written instructions and video don’t mention the corn syrup.
Oh wow how embarrassing! thanks for catching that! I have updated the post!
Ingredients are correct: Sugar 1 cup (200g)
Corn Syrup ½ cup (120ml)
Water ¼ cup (60ml)
Vegan Butter 2 Tablespoons (28g)
Baking Soda 1 teaspoon
Unsalted Raw Peanuts 1 cup (150g)
Method:
Combine the sugar, corn syrup and water in a heavy sauce pot and bring to a boil.
Once it boils, Insert a candy thermometer and continue to boil without stirring until it is 309°F (*See note above) it should just start to turn golden brown, then add the vegan butter, baking soda, vanilla extract and peanuts.
Spread mixture on a lightly oiled sheet pan and let cool
Hi Gretchen, it looks like there are two sets of peanut butter fudge ingredients on here? I will be using corn syrup and butter, which recipe should I use? Thank you!
I took this cake out of the oven an hour ago, couldn’t help cutting a small taste off the top before it goes into the freezer to stack and fill another day…but I had to leave a review for this because it was so good that it is easily the best dessert I’ve eaten all YEAR. It is best described as the best peanut butter cookie you have ever had in your life in cake form. So if anyone reading this is on the fence, go, run and get your peanut butter!????
wow! Thanks for the review!
HI! i was wondering for the peanut butter fudge recipe you have peanut butter 1 cup writen and creamy peanut butter 1 cup, whats the difference???
Hi! Thanks for pointing that out! Wow this recipe was crazy chaos to read! Yikes! When I implemented the “jump to recipe” button it really messed with so many of my recipes! I suspect that’s what happened here – or else I was just out of my mind when I wrote it!
This one had double ingredients all over the place! At any rate I’ve updated the entire post, refresh your cache and let me know it is reading more clearly! Thanks again!
Thank you so much!!