The World’s Best Chocolate Oatmeal Cake

Why do people love free food?

Chocolate chips in a white bowl.

It’s so embarrassingly true. It doesn’t matter if it’s last year’s leftover Halloween candy rejects or stale crackers from yesterday’s meeting. It’s like a science – people walk into the lunchroom, cafeteria, or whatever else you call an eating place at work and start scanning to see if there are any freebies on the counter. And if you want some, you’d better get moving. They will be gone in twenty seconds. Ten seconds. Five. Gone.

Chocolate drizzle over a cake.

Speaking as a teacher, I think that we, as a profession, are probably worst at treat hoarding. We exhaust our patience and sanity working with crazy sweet little people all day, and then we open the door into the teacher’s lounge and BAM. There they are. The treats. And with all reasonableness left somewhere between the behavior charts and excessive pencil sharpening and nose picking, suddenly we’re up to our elbows in some snack mix that we don’t even really like.

We = me.

Chocolate oatmeal cake with fudge frosting in a tin.

At my old school in Minnesota, we had a weekly treat day. Treats could be anything from a Panera bagels and cream cheese smorgasbord to a taco bar to my personal favorite – a treasure box of assorted donuts from Cub Foods. OMG. I love donuts.

One time, this cake mysteriously appeared on the counter in our teacher’s lounge. Like, this very cake that you see here today. Luckily I had the sense to snarf down an extra large piece (or two?) before the first bell and it only took one bite before I realized that this was indeed The World’s Best Chocolate Oatmeal Cake. It just happens to have oatmeal in it. Yes, that feels random to me too. Anyways, I was deliriously happy. Some fellow teachers weren’t so lucky.

One piece of chocolate oatmeal cake on a white plate with a fork.

That cake was gone before 8am, and here’s the thing: our school isn’t that big. I’m telling you. We are treat hoarders.

The baker of this thing of pure beauty turned out to be my coworker, Mimi, and better yet, her grandma turned out to be the holder of the original recipe. So. Mimi and her grandma. They ROCK.

Chocolate oatmeal cake on a fork and on a plate.

The cake is amazing. Lightly chocolatey, super moist, studded with chocolate chips, and topped with an old fashioned chocolate marshmallow frosting. The kind that crystallizes and gets little cracks in it when you slice into it. LOVE.

Chocolate oatmeal cake on a plate and a fork.

I don’t even have anything to say about the oats. It’s a delicious mystery.

I see this tablescape in your future. Very soon.

Chocolate oatmeal cake slice on a white plate.
A picture of The World’s Best Chocolate Oatmeal Cake

The World’s Best Chocolate Oatmeal Cake


This world’s best chocolate oatmeal cake recipe is from my coworker’s grandma. Made with chocolate chips, cocoa, and oatmeal, topped with fudge frosting.


  • 1 cup brown sugar
  • 1 cup white sugar
  • 1/2 cup butter, melted
  • 2 eggs, lightly beaten with fork
  • 1 3/4 cups flour
  • 1 teaspoon baking soda
  • 1/2 teaspoon salt
  • 1 1/2 tablespoons unsweetened cocoa powder
  • 1 cup quick cooking oats*
  • 1 3/4 cups boiling water
  • 1 12 oz bag chocolate chips, divided (go for the Ghirardelli*)
  • 6 tablespoons butter
  • 6 tablespoons milk
  • 1 1/2 cups sugar
  • 1/23/4 cup chocolate chips (Ghirardelli again, please)
  • 1/23/4 cup mini marshmallows*


  1. Preheat oven to 350. With an electric mixer, cream the butter and sugars. Add the eggs and mix well.
  2. Add flour, soda, salt and cocoa and mix until just incorporated. The batter will be very thick.
  3. Add water to oatmeal and let stand for a few minutes. Once oats are soft, add oats/water mixture to the batter and mix well. Stir in half of the bag of chocolate chips (6 ounces).
  4. Pour into a greased or buttered rectangular 9×13 cake pan. Sprinkle the top of the cake with the rest of the bag of chocolate chips (6 ounces).
  5. Bake at 350 for 30-40 minutes or until the surface springs back lightly when touched and your house smells amazing. Do not overbake. Let cool completely.
  6. For the frosting, melt the butter, sugar, and milk in a large saucepan over medium-low heat. Bring to a boil and boil for 30 seconds.
  7. Reduce heat to low and add chocolate chips and marshmallows. Stir or whisk until frosting is smooth. Pour immediately over the cooled cake. The frosting crystallizes almost immediately as it cools so it’s important to get it on the cake while it’s still piping hot. Allow the frosted cake to cool for 5 minutes before serving. Or… not.


*You can substitute rolled oats for the quick cooking oats, but they should be soaked in the boiling water for at least 10 minutes. Also, if you use rolled oats, the texture of the cake will be different as the oats will be more noticeable.

*Any chocolate chips will work.

*Regular size marshmallows work, too. They just take longer to melt.

  • Prep Time: 15 mins
  • Cook Time: 45 mins
  • Category: Dessert
  • Cuisine: American

Keywords: chocolate cake, chocolate oatmeal cake, oatmeal cake

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Guess what else? Mimi is going to need a lot of chocolate cake in the coming months because she’s pregnant with TWIN BABY GIRLS! Chocolate cake and baby girls. That’s the best kind of life.

Thanks Mimi and Mimi’s grandma for letting me share The World’s Best Chocolate Cake with… the world. Yummy.

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