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Apple Cobbler Sheet Cake with Brown Butter Buttercream

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Apple Cobbler Sheet Cake with Brown Butter Buttercream, apple pie filling, and fresh apple slices on top!
Servings 12 Slices
Author Mandy Merriman - Baking with Blondie

Equipment

  • 9x13 pan
  • Ateco 868 open star piping tip

Ingredients

Apple Filling

  • 2 cups finely cubed granny smith apples About 2 large apples
  • 1 Tablespoon lemon juice
  • 1/2 cup brown sugar
  • 2 teaspoons cinnamon
  • 1 pinch salt
  • 1/8 cup water
  • 1/4 cup slurry (1/4 cup water + 1 teaspoon cornstarch, stirred to combine)

Brown Butter Cinnamon Buttercream

  • 1 1/2 cup unsalted butter 1/2 cup (or 1 stick) will be made into the browned butter, and the other cup (or 2 sticks) will be left as is.
  • 1 teaspoon vanilla
  • 1 teaspoon cinnamon
  • 1 pinch salt
  • 1/4 cup heavy cream + more if needed
  • 6-7 cups powdered sugar

Apple Cake

  • 3/4 cup buttermilk room temperature
  • 4 egg whites room temperature
  • 1/4 cup sour cream room temperature
  • 1/3 cup applesauce
  • 1/3 cup vegetable oil
  • 1 teaspoon vanilla
  • 1 teaspoon cinnamon
  • 1 15.25oz White Cake Mix Box I used Duncan Hines for the best texture and taste

Oatmeal Crumble

  • 1 cup old fashioned oats
  • 1 cup flour
  • 1/2 cup brown sugar
  • 1/4 cup granulated sugar
  • 1 teaspoon cinnamon
  • pinch of nutmeg
  • 1/2 cup (or 1 stick) unsalted butter, softened to room temperature

Garnish

  • thin slices of green apples soak in lemon juice if you're not serving within the hour.

Instructions

For the Apple Filling

  • In a large bowl, mix together the apples, lemon juice, brown sugar, cinnamon, salt, and water. Add to a pan over medium high heat and bring to a boil/bubble. Turn the heat down to low/medium and let simmer for 10 minutes until the apples are tender.
  • Add in the slurry and stir. Cook for 2-3 minutes, then add to a glass bowl. Cover, and place in the fridge until you're ready to assemble the cake and the filling has completely cooled.

For the Apple Cake

  • Preheat the oven to 325 degrees, then prep a 9x13 sheet pan with nonstick spray. Set aside.
  • In a large bowl, whisk together everything (except for the cake mix) until it's thoroughly combined. Sift in the cake mix and gently fold in (don't overmix). Spread into the prepared cake pan, then bake for 25-27 minutes. Let cool completely before assembling on the rest of the cake components.

For the Crumble

  • Preheat the oven to 350 degrees. In the bowl of a stand mixer fitted with a paddle attachment, mix together all the ingredients except for the butter. Add in the butter until a loose crumble forms, medium speed for about 1 minute. Spread the crumble out onto a cookie sheet and bake for 10 minutes (using a spatula to move/mix things around halfway through). Let cool completely.

For the Browned Butter Buttercream

  • To make the browned butter (make 30 min in advance!), melt one of the sticks (1/2 cup) of butter in a saucepan over medium heat. Wait until it bubbles, then foams. When it foams, keep stirring and wait for a nutty aroma. Stay close and keep stirring - when it turns an amber color, pour the browned butter into a bowl (make sure to scrape out the browned butter bits into the bowl). Let cool into a solid in the fridge for a half hour before using.
  • In the bowl of a stand mixer fitted with a paddle attachment, whip up the browned butter until it's light and fluffy, then add in the other 1 cup (or 2 sticks) of butter and whip up again until it's light and fluffy. Add in the vanilla, salt, cinnamon, and heavy cream and whip up again. Slowly add in the powdered sugar with the speed on low. When it's all incorporated, it will be thick, add in a touch of heavy cream (1 Tablespoon or so more), then whip it up again on high speed until it's light and fluffy. Use a wooden spoon to hand-beat out the air bubbles until it's smooth.

Assembly

  • Fill a large piping bag with the 868 piping tip and buttercream - set aside. Spread the rest of the buttercream in a flat layer on the cooled cake. Spread on the apple filling, then add on a layer of the crumble. Pipe on a shell border around the outside of the cake, then lay out fanned apple slices. Serve chilled for cleaner slices. Enjoy!