This easy chocolate brownie cake is an old-fashioned recipe that gives you the the taste of chocolate walnut brownies in sheet cake form. Just like grandma used to make!
Grandma’s Brownie Cake
A few years ago my grandma gave everybody in the family a cookbook of recipes that she loves along with some fun stories to go along with it.
Talk about vintage recipes right? Some of them I’m not sure how to try because ingredients aren’t readily available anymore. Some of them have been family favorites for years like this homemade chicken noodle soup and pizza loaf.
And some of them – like his chocolate brownie cake – have become new favorites! I remember having these growing up but just recently tried making them on my own, and they’re just as good as I remember.
You’ll love this recipe because
- It tastes like a classic recipe you grew up eating (tastes like it because it is!)
- It’s easy to make for a crowd and one everyone always enjoys
- You can make it with or without the nuts for allergies
- It tastes like a delicious chocolate walnut brownie but with a bit more of a cake texture.
Ingredients
Ingredient Notes
- Buttermilk – if you don’t have buttermilk, combine 1/2 cup milk with 1/2 TBS lemon juice or distilled white vinegar and let it sit for about 10 minutes. Homemade buttermilk!
- Chopped walnuts – I prefer this with the walnuts on top but just like in this chocolate chip zucchini bread, the walnuts are optional if you’re concerned about nut allergies.
Instructions
Preheat your oven and grease a large baking sheet like this one.
Mix the flour and sugar in a large bowl and set aside.
Heat a pot on the stove over medium-high heat to start making the chocolate part of the batter.
Melt butter. Once melted, add your cocoa powder and water and bring the mixture to a boil.
Add the boiling chocolate mixture to the flour mixture from earlier and stir until well combined.
Add buttermilk, eggs, baking soda, and vanilla to the mixture and combine until you have a nice smooth batter.
Pour the batter into the prepped baking sheet and bake in the oven for 20-22 minutes or until the cake is cooked all the way through.
While the cake is baking, make your icing. It’ll seem very similar to what you did for the cake batter but the results are totally different.
Start by heating a pot to medium-high heat and adding butter. Melt the butter then add the cocoa and milk to the melted butter.
Bring the mixture to a boil.
Put your powdered sugar into a small bowl then pour the boiled mixture (deja vu anyone?) over the powdered sugar and stir to combine to make your icing.
Ice cake within five minutes of removing cake from the oven.
Top with chopped walnuts if desired. If not, you’re done and skip the final step – cutting the cake!
Allow the cake to cool completely then cut into squares and serve either by itself or a la mode with a little (or a lot) of ice cream.
Or go all out and make it a chocolate brownie cake sundae! That sounds pretty delicious right about now!
Expert Tips
Add the walnuts immediately after adding the icing rather than waiting until it hardens. This will keep the nuts from falling off when you slice the cake (kind of like dipping rainbow donuts in sprinkles while the frosting is still warm).
Use a spatula to make sure that the chocolate brownie cake batter spreads around the entire sheet pan in one even layer.
Leave the chocolate brownie cake in the pan rather than slicing it all and removing for storage. I recommend just covering it with something like this sheet pan lid.
Remove the chocolate mixtures from heat as soon as they start boiling, don’t let them keep boiling or you’ll lose some of the moisture in the cake and icing.
Use a small rectangle spatula to remove the cake squares from the pan without destroying the rest of the squares.
Recipe FAQs
This recipe was written for the size of a sheet pan, so I do not recommend making this in round or a 9×13 cake pan. The thickness of the cake will be off and not cook the way you want it to.
You can freeze this chocolate brownie cake for up to six months. I recommend slicing into squares and freezing squares in individual plastic bags if possible so the icing doesn’t freeze the squares together.
Store this chocolate brownie cake either in an airtight container or with a sheet pan lid on top for up to a week.
A chocolate brownie cake is a chocolate cake with chocolate icing that you cut into squares like brownies rather than slices like cake.
More Chocolate Desserts
- Striped delight
- Snickers poke cake
- Reese’s peanut butter pie
- Homemade moon pie recipe
- Peanut butter s’mores bars
Old-Fashioned Chocolate Brownie Cake
Ingredients
Brownie Cake
- 2 cups flour
- 2 cups sugar
- 3/4 cup butter
- 2 TBS cocoa powder
- 1 cup water
- 1/2 cup buttermilk
- 2 eggs
- 1 tsp baking soda
- 1 tsp vanilla
- 1/2 tsp salt
Icing
- 1/2 cup butter
- 1 TBS cocoa
- 6 TBS milk
- 2 cups powdered sugar
- 1 cup chopped walnuts
Instructions
Brownie Cake
- Preheat your oven and grease a large baking sheet.
- Mix the flour and sugar in a large bowl and set aside.
- Heat a pot over medium-high heat on the stove. Melt butter in pot.
- Once melted, add your cocoa powder and water and bring the mixture to a boil.
- Add the boiling chocolate mixture to the flour mixture from earlier and stir until well combined.
- Add buttermilk, eggs, baking soda, and vanilla to the mixture and combine until you have a nice smooth batter.
- Pour the batter into the prepped baking sheet making sure to evenly spread it across the entire sheet pan.
- Bake cake in the oven for 20-22 minutes or until cake is cooked all the way through.
- Ice cake within five minutes of removing cake from the oven.
- Top with chopped walnuts if desired.
- Allow cake to cool completely then cut into squares and serve.
Icing
- Heat a pot over medium-high heat on the stove. Melt butter in pot.
- Add cocoa and milk to melted butter and bring to a boil.
- Put your powdered sugar into a small bowl then pour the boiled mixture over the powdered sugar and stir to combine to make your icing.
Ashley says
Such a great recipe! Love the brownie in cake form!
Britni Vigil says
me too! It’s one of our favorites!
Denay DeGuzman says
This chocolate cake was a big hit at my house! Next time around I’ll be making two cakes at the same time so I can drop one off at my parents’ home. I know they would really enjoy a little surprise treat like this!
Britni Vigil says
Ooh that’s such a nice idea for your parents!