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flipper spatula serving slice of gluten-free Texas sheet cake

Aunt Jennie's Gluten-Free Texas Sheet Cake

Best ever recipe for moist gluten-free Texas sheet cake, topped with rich, fudgy chocolate icing. Easy dessert anyone can make!
5 from 1 vote
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Course: Cakes, Desserts
Cuisine: American
Diet: Gluten Free
Prep Time: 30 minutes
Cook Time: 30 minutes
Total Time: 1 hour
Servings: 24
Calories: 317kcal
Author: Mel Lockcuff






  • Pre-heat the oven to 350º F and grease a 16x10x1 sheet cake pan.
  • In a large mixing bowl, whisk together the flour, xanthan gum, baking soda, sugar, and salt.
  • In a medium saucepan, melt the butter.
  • Then add the cocoa powder and water, whisking together.
  • Bring this mixture to a boil over low to medium heat.
  • Then pour the cocoa mixture over the dry ingredients.
  • Add the buttermilk, eggs, and vanilla extract, mixing well 'til everything is well-combined.
  • Pour the cake batter into the greased sheet cake pan.
  • Bake at 350º F for 25-30 minutes, or until a toothpick or cake tester inserted into the center comes out clean.


  • While the cake is baking, melt the butter in a medium saucepan.
  • Whisk the cocoa powder and buttermilk into the butter.
  • Bring this mixture to a boil over low to medium heat.
  • Remove it from the heat, and whisk in the powdered sugar, vanilla extract, and nuts, if desired.
  • Mix or whisk 'til the mixture creates a smooth chocolate frosting.
  • Then pour the frosting over the cake while it's still hot, spreading the frosting all over the cake 'til even and smooth.
  • Once it's cooled, it's finally time to slice, serve, and enjoy!


*I almost always use Authentic Foods Classical Blend gluten-free flour. Time and time again, this flour blend has given me the best results and gluten-free baked goods that taste no different than the original. Do keep in mind that different gluten-free flours can give different results.
*Some gluten-free flours already contain xanthan gum, so be sure to check the ingredients in your flour before adding more. Too much xanthan gum or baking powder can give off a soapy flavor.
*If you don't have any buttermilk on hand, you can make a 1:1 substitute by whisking vinegar and milk together. Use 1 tablespoon of vinegar per 1 cup of milk, and be sure to let it sit for 5-10 minutes, allowing it to curdle before using.
How do I store Texas sheet cake, and how do I keep it moist?
Seeing as this recipe uses a buttermilk icing, it is best that you store your finished cake in an airtight container in the refrigerator for up to 2-3 days. After that, it will start to lose its texture and can even grow more dense.


Calories: 317kcal | Carbohydrates: 44g | Protein: 3g | Fat: 16g | Saturated Fat: 8g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 5g | Trans Fat: 1g | Cholesterol: 45mg | Sodium: 224mg | Potassium: 83mg | Fiber: 2g | Sugar: 35g | Vitamin A: 385IU | Vitamin C: 1mg | Calcium: 29mg | Iron: 1mg
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