This is my favorite chocolate cake recipe because it’s easy to make, ready in under an hour, and reminds me of the famous Portillo’s chocolate cake from Chicago! You might know this as “chocolate mayonnaise cake” – a moist chocolate cake, rich and chocolatey, covered in a thick layer of chocolate buttercream frosting, and layered for a decadent dessert. The perfect base for my homemade Portillo’s Chocolate Cake Shake.
Don’t run away just because of the name! Mayonnaise is an ingredient that’s doing triple duty, and you would never know that it’s included if I didn’t tell you.
Which I have to… so you can make it… yeah.
But really… mayonnaise?
I pretty much avoid mayonnaise unless I’m making a big batch of my copycat Ruby Tuesday pasta salad, and the other exception is this cake.
Mayonnaise is generally just a mix egg yolks, oil, vinegar and salt. And if you think about most cake recipes, they call for eggs, oil, salt and sometimes also vinegar – so the mayo is covering the jobs of all those ingredients at once!
So don’t let the idea of adding mayo to this chocolate cake gross you out, because I promise there’s no aspect of the completed cake that will deter you from falling in love with it.
Portillo’s Chocolate Cake Copycat
I call this my Portillo’s Chocolate Cake copycat recipe. If you don’t already know, I’m originally from Illinois and one of the things I miss the most about it (aside from the deep dish pizza because ooooooohmygod) is Portillo’s.
Portillo’s makes some of my favorites foods, and it’s the first place I stop when I go to visit. I order the same thing every time:
- Italian Beef sandwich, dry with gravy on the side
- Cheese fries (crinkle fries, to be precise)
- Chocolate cake shake
- And depending on how long I’m sticking around town, maybe also a chocolate cake, to go
While I don’t get to go home to Chicago often to indulge myself, the good news is that making my own decadent double chocolate layer cake at home couldn’t be easier – you know, aside from asking someone else to make it.
I normally wouldn’t call for using a box mix, but it’s honestly the easiest way to get the closest taste I want – so that’s exactly what we’re going to use!
Specifically, a box of Betty Crocker Super Moist Milk Chocolate cake mix. You could use a different brand, but to me this one is the best flavor.
How to level a cake
Use a cake leveling tool. I like to use a cake leveler like this – you just adjust the height on each side and hold on to the top while you glide it through the cake from one side to the other.
Use a serrated knife. Place your knife at the edge of the cake dome and hold the blade parallel to the counter while you slice into the cake a few inches. Now remove the blade, turn the cake a quarter turn and do the same thing again. Work your way the rest of the way around the cake, and then take one final parallel slice all the way through to remove the top.
Use a ruler, toothpicks and unflavored dental floss. You may have seen this viral hack in a video at some point. You use a ruler to measure up from the bottom of the cake and insert a toothpick where you want the layer that’s going to be removed.
Turn the cake an eight turn and do the same thing, all the way around. Now wrap the dental gloss (again – unflavored, my friends) around the cake, resting on top of each toothpick. Cross the ends of the floss and pull straight across – this will pull the floss through and slice the cake.
For what it’s worth, this will be the least clean of the three methods, but hey – a hack is a hack, right?
How to frost a layer cake
There’s no need to be intimidated by decorating a layer cake! Especially this one – we’re not doing any crazy fondant, or intricate piping.
- Use an icing spatula to spread about ⅓ of your frosting on top of the first layer of cake, within about ¼″ around the edge.
- Place the second layer on top, making sure you have it centered and lined up with the bottom layer.
- Coat the sides of cake with a thin layer of frosting – this is called the “crumb layer” or “crumb coat”. It seals in any crumbs that might manifest as you’re frosting.
- Now you’ll frost the outside of the cake with the rest of your frosting, in whatever way you’d like!
I like to use the cake tops that are leftover from when we leveled the tops of the cake rounds as a decoration, because it’s simple and avoids waste. Just crumble them and place them on top – boom, decorated.
The result is a moist, rich, double chocolatey layer cake with a beautifully thick layer of chocolate buttercream frosting.
This is the kind of cake that you probably want to slice into 16 thinner slices, instead of 8 large ones. It’s indulgent and sweet enough that a larger slice is probably too much to handle.
… that’s not to say I haven’t eaten a big slice with reckless abandon. I just knew as soon as I was done that I probably should have had a little self control because the sugar rush isn’t for the faint of heart!
I can’t put into words how much I love it, so you’ll just need to make it to experience it yourself.
After you’ve made this recipe, please consider coming back to share your experience with others by leaving a comment below with a star rating!
Double Chocolate Layer Cake (Chocolate Mayonnaise Cake)
- 1 box, 15.25 ounces Betty Crocker Super Moist Milk Chocolate cake mix
- 3 large eggs, room temperature
- 1 cup water
- 1 cup mayonnaise
- 10 ounces semisweet, milk, or dark chocolate chips
- 1 ½ cups unsalted butter, room temperature
- 3 cups powdered sugar
- 1 Tablespoon vanilla extract
- Preheat oven to 350°F. Spray two round cake pans with non-stick spray and set aside.
- In a large bowl, combine cake mix, eggs, water and mayonnaise and beat with a hand or stand mixer on medium speed until well combined.
- Pour half of the batter into each of the prepared pans, and bake for 25-30 minutes or until a toothpick inserted into the center comes out with moist crumbs.
- Let cool in pans for 5 minutes, then carefully remove from pans and transfer to wire racks to cool completely.
- Once cooled, level off the top of one of the cakes (this will be your bottom layer). You can also level off both if you'd like the top to be flat as well. Set aside the pieces you've shaved off the tops and set aside.
- In a double broiler or in the microwave, melt chocolate until smooth and set aside to cool.
- In a large bowl, beat butter with a stand mixer or hand mixer until smooth.
- Add powdered sugar and beat until well combined, starting on low speed and increasing as the powdered sugar incorporates.
- Add vanilla extract and melted chocolate, and beat until well combined and smooth.
- Place the leveled off cake layer on a platter and frost the top with ⅓ of the prepared frosting. Top with second cake layer and frost the top and sides of both layers with remaining frosting.