The first time I made this recipe, my family was skeptical. “Why would you put oatmeal in a cake?” they asked. While it initially seems like an odd addition, the oatmeal is what transforms this cake from mediocre to marvelous. The old-fashioned oats hold on to moisture while becoming invisible within the body of the cake. This oatmeal cake with coconut frosting is spongy and yet light, with a crunchy topping and a pleasantly sweet center. The best part? It can go from pantry to table in under an hour.
Jump to RecipeThe coconut “frosting” in this bake is more of a topping, which we will broil during the final step of this recipe. While this is certainly non-standard as far as cakes go, don’t worry – even my frosting-obsessed husband loved how this cake turned out.

This oatmeal cake with coconut frosting is one of my favorite “oh crud, I forgot I promised to bake a dessert for a friend gathering” recipes. The ingredients are all things I tend to have in my pantry, and the whole cake can be ready in less time than it takes for me to go grocery shopping. Because the frosting is more of a broiled crunchy topping, you don’t need to wait for the cake to cool in order to add the frosting and finish the cake.
If you’re looking for other quick and easy dessert recipes, check out my recipe for Symphony brownies, or perhaps these cookies & cream krispie treats.

Ingredients
For the cake, you’ll need:
- Old fashioned oats – not quick oats or steel cut oats. You could try using quick oats, but they may not hold on to moisture quite as well as the standard “old fashioned” variety.
- Boiling water. You can boil the water using an electric kettle (my preference) or in the microwave. It’s okay if the water isn’t exactly boiling, as long as it’s hot enough to effectively combine with your oatmeal
- Both granulated sugar and brown sugar
- Softened butter
- Vanilla bean paste
- Eggs
- All-purpose flour
- Several spices, including ground cinnamon and nutmeg
- Both baking soda and baking powder
- Just a pinch of salt
For the coconut frosting, you will need:
- Coconut flakes – I used unsweetened for this recipe. If you only have sweetened coconut flakes, cut the amount of brown sugar in half.
- Brown sugar
- Melted butter
- Half-and-half – though you can substitute milk or cream.
How to make oatmeal cake with coconut frosting
Combine boiling water and old-fashioned oats in a small bowl and allow to cool.(And maybe give your housemates a heads up that no, this isn’t a bowl of oatmeal you generously made them for breakfast.)

Preheat your oven to 350 degrees F and grease a 9” by 13” baking dish.
Using an electric mixer, beat together the butter and sugars for the cake. Mix in the vanilla bean paste and eggs until the mixture is completely combined.
In a separate bowl, combine flour, baking soda, baking powder, salt, cinnamon and nutmeg. Slowly add this to your butter mixture. Once combined, pour in oatmeal mixture. Beat until completely combined.

Pour your batter into the prepared baking dish. Bake for 30-35 minutes, or until a toothpick comes out clean. While the cake is baking, combine all of the topping ingredients in a small bowl.

As soon as the finished cake comes out of the oven, cover it with the coconut topping. Return the topped cake to the oven and broil on high for 2-3 minutes, watching closely. Remove from the oven once the coconut is slightly browned and the topping of your oatmeal cake with coconut frosting is bubbly.

Allow the cake to cool briefly before slicing and serving. If stored in an airtight container, this oatmeal cake with coconut frosting will stay fresh for up to a week. The broiled coconut topping helps to hold in the moisture; personally, I think this cake tastes bests on day 2 or 3 after baking, as long as it’s been stored correctly.
I hope you enjoy this oatmeal cake with coconut frosting! If you make it at home, feel free to tag any of your social media photos with @WhiskAverseBaking, or leave a message in the comments below. You can also tap the “Pin Recipe” button in the recipe card to save this recipe for a rainy day.

Oatmeal Cake with Coconut Frosting
Equipment
- 9” x 13” baking dish
Ingredients
Cake
- 1 cup old fashioned oats
- 1 ½ cups boiling water
- ¾ cup granulated sugar
- ¾ cup brown sugar
- ½ cup butter softened
- 1 teaspoon vanilla bean paste
- 2 eggs
- 1 ¼ cups flour
- 2 teaspoons ground cinnamon
- 1 teaspoon baking soda
- ½ teaspoon baking powder
- ¼ teaspoon nutmeg
- ¼ teaspoon salt
Topping
- 1 cup coconut flakes
- ½ cup brown sugar
- ¼ cup butter melted
- ¼ cup half-and-half
Instructions
- Combine boiling water and old-fashioned oats in a small bowl and allow to cool.
- Preheat oven to 350 degrees F and grease a 9” by 13” baking dish.
- Using an electric mixer, beat together the butter and sugars for the cake. Mix in the vanilla bean paste and eggs until the mixture is completely combined.
- In a separate bowl, combine flour, baking soda, baking powder, salt, cinnamon and nutmeg. Slowly add this to your butter mixture. Once combined, pour in oatmeal mixture. Beat until completely combined.
- Pour your batter into the prepared baking dish. Bake for 30-35 minutes, or until a toothpick comes out clean.
- While the cake is baking, combine all of the topping ingredients in a small bowl. As soon as the finished cake comes out of the oven, cover with the topping.
- Return the topped cake to the oven and broil on high for 2-3 minutes, watching closely. Remove from the oven once the coconut is slightly browned and the topping is bubbly.
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