Samoas-Style Gluten Free Chocolate Sheet Cake
Ingredients
1 1/4 cups (100 g) unsweetened coconut flakes
For the cake
1 cup (140g) all-purpose gluten-free flour
1/2 teaspoon xanthan gum (omit if your blend already contains it)
3 tablespoons (15g) unsweetened cocoa powder (Dutch-processed works best but natural will work fine)
1 cup (200 g) granulated sugar
1/2 teaspoon baking soda
1/8 teaspoon kosher salt
8 tablespoons (112g) unsalted butter, chopped
1/2 cup (4 fluid ounces) brewed coffee (can replace with an equal amount water)
1/2 cup (112g) sour cream, at room temperature
1 egg (60 g, weighed out of shell) at room temperature, beaten
1/2 teaspoon pure vanilla extract
For the icing
1 3/4 cups (200 g) confectioners’ sugar
1/8 teaspoon kosher salt
1/2 cup (109 g) packed light brown sugar
8 tablespoons (112g) unsalted butter, chopped
1/4 cup (2 fluid ounces) milk
1 teaspoon pure vanilla extract
3 ounces semi-sweet chocolate, melted
Instructions
First, toast the coconut. Preheat your oven to 325°F. Place the coconut chips in a single layer on a rimmed baking sheet lined with unbleached parchment paper. Place the baking sheet in the center of the preheated oven and bake until the chips are lightly golden brown all over and smell fragrant (about 5 minutes). Remove the flakes from the oven and allow to cool slightly before crushing the toasted flakes in your hands. Set aside.
Make the cake. Preheat your oven to 325° F. Line a quarter sheet pan (9 x 13 x 2-inches) with unbleached parchment paper and set it aside. In a large bowl, place the flour, xanthan gum, cocoa powder, sugar, baking soda and salt, and whisk to combine well. Set the bowl aside. In a small saucepan, heat the butter and coffee on medium heat, stirring occasionally, until the butter is completely melted. Pour the melted butter and coffee mixture over the dry ingredients, and mix to combine. Add the sour cream, egg and vanilla, and mix to combine. Pour the batter into the prepared sheet pan, and spread into an even layer with a wet spatula. Place the baking sheet into the preheated oven and bake until the cake is uniform and springs back readily when pressed gently with a finger, about 20 minutes.
During the last 5 to 10 minutes of the cake’s baking, make the icing. In a large bowl, place the confectioners’ sugar, salt and brown sugar and whisk to combine well, working out any lumps in the brown sugar. Set the bowl aside. In a clean small saucepan, place the chopped butter and the milk, and cook over medium heat, stirring occasionally, until the butter is completely melted. Remove the saucepan from the stove, add the vanilla and mix to combine. Pour the hot butter and milk mixture over the dry ingredients, and mix to combine.
Ice the cake. As soon as the cake is finished baking, remove the pan from the oven and pour the hot icing over the hot cake. Working quickly to ensure that the icing is spread before it sets, with an offset spatula or butter knife, spread the icing over the entire surface of the cake with an offset spatula or knife. Sprinkle the top of the cake evenly with the crushed toasted coconut chips. Allow the cake to cool to room temperature in the pan. Once the cake is cool, drizzle the top in zig-zag patterns with the melted chocolate. Once the chocolate has set, slice into 8 to 10 pieces, and serve chilled or at room temperature. The cake is easiest to slice with a warm, sharp knife when the cake itself is cold.
Adapted from Chef-In-Training’s recipe for Samoa Sheet Cake and my recipe for Gluten Free Texas Sheet Cake.
