Can you believe how gorgeous this cake is?! My goodness, this has been such a fun series and we’re already halfway through! This time, we have the most delicious Berry Cobbler Cake with oatmeal crumble made into a sheet cake! Is it technically just a cobbler? Either way, it’s one of my top 5 favorite cakes of all time and it’s finally here in a stunning sheet cake!

So if you’re a berry fan, and love a little crumble on top, this cake is right up your alley. And the best news is that it’s pretty simple to make. Yes, there are lots of different elements of this cake, but separately they’re simple, and the décor is easy to master on the first try.

Can I make this into a stacked cake or cupcakes instead?

Of course! My stacked cake version is right here.

If you’d like to make them into cupcakes, DANG that’s going to be delicious, too! Just split the batter into the 24 cupcakes, bake for 12-15 minutes, then slather on the filling, crumble and swirl the buttercream on top. OR you can hollow out the cupcakes, add in the filling, swirl on the buttercream, and dip the whole thing in the crumbles. The possibilities are endless! Just make sure to get those tasty elements on each cupcake.

However, this version of the most delicious Berry Cobbler Cake with oatmeal crumble has my heart forever. Why? Its a cobbler, it’s a cake, it’s all the things.

Can I decorate this outside of the sheet pan?

Yes! Just flip the cake out onto your serving plate, pipe a dam around the outside top of the cake, add the filling, the crumble, then add on the decor on top. This Berry Cobbler Sheet Cake with Oatmeal Crumble can me made however you’d like! I’m just sharing a fun way I chose to decorate it this time.

How to make a berry cobbler sheet cake

The ingredients are delicious, and don’t need to be seasonal. I know how berries taste perfect only a couple times a year – but frozen will work beautifully anytime! Here’s how:

Ingredients

  • Buttermilk
  • Sour Cream
  • Egg whites + 1 egg
  • Vegetable Oil
  • Vanilla
  • Almond Extract
  • White Cake Mix (I used Duncan Hines)
  • fresh berries

The directions are below, but trust me when I say they’re EASY! Just one bowl and whisk is needed.

what sheet pan can I use?

Any 9×13 sheet pan will do. I used one very similar to this: HERE, but you can use a metal or glass one and it will work just as well.

How to make berry filling for cake

Instead of putting the filling between the layers, this time we’re slathering it right on top! To make the berry filling, just combine the ingredients except for the cornstarch in a saucepan and watch as it bubbles and thickens. Add in the cornstarch to thicken it up a little bit more, then let it cool completely before adding it on your cake. The full list of ingredients is below.

How to make the cinnamon oatmeal crumble

I LOVE how this crumble comes together fast! Just mix all the ingredients in a bowl of a stand mixer, spread it out onto a cookie sheet to bake into a crumbly topping, let it cool, then add it on your cake! It’s also yummy on granola :).

The full directions are below for this one, too.

Here’s a video of the process, including the frosting method:

If you make a Baking with Blondie bake, including my Berry Cobbler Sheet Cake with Oatmeal Crumble, I’d love to see it! Make sure to tag me @bakingwithblondie #bakingwithblondie so I can join in on all the fun.

Happy Baking!

xo, Mandy

Get the Recipe: Berry Cobbler Sheet Cake with Oatmeal Crumble

5 from 1 vote
Berry studded white cake with touch of cinnamon, berry compote filling, an oatmeal crumble, and a light and fluffy cinnamon vanilla buttercream.
Servings: 16 large slices, depending on size
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Ingredients
 

Berry Cinnamon Sheet Cake

  • 3/4 cup buttermilk, room temperature
  • 2/3 cup sour cream , room temperature
  • 3 whole egg whites, room temperature
  • 1 whole egg
  • 1/3 cup vegetable oil
  • 1 Tablespoon vanilla OR 1 teaspoon vanilla bean paste
  • 1 teaspoon almond extract
  • 1 teaspoon cinnamon
  • 1 15.25oz White Cake Mix (I used Duncan Hines)
  • 1 cup fresh mixed berries (blueberries, raspberries, blackberries, strawberries)

Triple Berry Filling

  • 3 cups frozen or fresh mixed berries
  • 2 Tablespoons lemon juice
  • 1/2 cup sugar
  • 1 1/2 cups water
  • 1/4 cup cornstarch

Oatmeal Cinnamon Crumble

  • 1 cup old fashioned oats
  • 1 cup all purpose flour
  • 3 Tablespoon granulated sugar
  • 1/2 cup brown sugar
  • 1/4 teaspoon salt
  • 1 teaspoon cinnamon
  • 1 pinch nutmeg
  • 1/2 cup unsalted butter, softened

Cinnamon Spiced Vanilla Buttercream

  • 3 sticks (or 1 1/2 cup) unsalted butter
  • pinch of salt
  • 1 Tablespoon vanilla
  • 1 teaspoon cinnamon
  • 1/4 cup heavy cream
  • 7-8 cups powdered sugar

Equipment

  • 9×13 sheet pan
  • 1M Piping Tip
  • small circle piping tip
  • piping bags

Instructions
 

For the Cake:

  • Preheat the oven to 325 degrees, prep a 9×13 pan with a swipe of shortening and dust of flour, set aside.
  • In a large bowl, hand whisk together the egg whites, egg, oil, vanilla, almond extract, sour cream, and buttermilk until thoroughly combined. Sift in the cake mix and gently stir until it's combined (don't overmix). Toss in the berries and gently fold in.
  • Spread the batter evenly into the prepared baking sheet. Bake for 27-30 minutes. Let cool completely before adding on the other cake elements. Make the oatmeal crumble, filling, and buttercream ahead of time or while the cake is baking.

For the Berry Filling

  • Stir everything except for the cornstarch in a saucepan over medium heat until the mixture begins to bubble. Stir and let cook for about 5 minutes until the berries reduce slightly, then add in the cornstarch. Stir until thickened, then store the filling in a bowl to cool completely in the fridge/freezer before slathering onto the cake.

For the Oatmeal Crumble

  • Preheat the oven to 350 degrees. In the bowl of a stand mixer fitted with a paddle attachment, combine all the ingredients until a light crumble forms. Spread the crumble out onto a sheet pan and bake for 10 minutes, then stir. Bake for another 5 minutes until lightly toasted, then let cool completely before sprinkling onto the cake.

For the Buttercream

  • In a bowl of a stand mixer fitted with a paddle attachment, whip up the butter until it's light and fluffy. Add in the salt, vanilla, cinnamon, and heavy cream, and whip it up until everything is combined. With the mixer on low speed, slowly add in the powdered sugar. Flip the speed to high and whip up the buttercream until it's light and fluffy in texture and color. Find a 1M and small circle piping tip. Fill one bag with the 1M (about 2 cups) and buttercream, and another piping bag with the circle piping tip and buttercream. Set aside.

Assembly

  • Slather on a thin layer of buttercream on the sheet cake with an angled icing spatula.
  • Slather on all the filling, then sprinkle on the oat crumble. Press down gently to make it as flat as possible.
  • Pipe on the lines as shown in the video above with the circle piping tip, then pipe a shell border around the outside with the 1M piping tip. Enjoy!