Gluten-Free Texas Sheet Cake

This is the gluten-free Texas chocolate sheet cake recipe you’ve been waiting for! All the classic chocolate flavor & delicious texture you love–just made gluten-free!

This gluten-free chocolate cake recipe was a request by a reader (I LOVE getting your recipe requests!), and I’ve been SO excited to share it since nailing down the recipe a few weeks ago. Because WOW IT IS SO GOOD.

If you’ve never had it before, Texas sheet cake is one of the easiest chocolate cake recipes out there. You don’t need any fancy piping bags or special decorating skills to make it. It’s famous at parties, get-togethers, reunions, and celebrations of all kinds–in part, because it’s so simple to make, in part because it can easily feed a crowd at a large gathering, and in part because HAVE I MENTIONED IT IS DELICIOUS?!

This rich chocolate cake is made in a sheet pan and covered with a simple chocolate fudge frosting that works its own magic on the flavor and texture of the cake. One bite in, and I think you’ll love it as much as we do!

Here’s what you need to make the best gluten-free Texas sheet cake…

Start With Simple Ingredients

Okay, chocolate lovers! Let’s get started with a peek at our ingredients list:

• Gluten-Free Measure-For-Measure Flour. I highly recommend King Arthur Measure For Measure Gluten-Free Flour, but if you use another 1:1 gluten-free flour blend, be sure it contains xanthan gum for best results. (Do not substitute almond flour, oat flour, or coconut flour into this recipe.)
• Sugar keeps this cake super moist & gets divided between 24-36 servings!
• Baking Soda & Salt. This helps keep the cake’s texture light & level, and helps balance the flavor.
• Sour Cream (Or Buttermilk). Most traditional texas sheet cake recipes use either buttermilk or sour cream. The acidity reacts with the baking soda to give the cake a light texture, and the tang balances the flavor. I recommend using sour cream first, buttermilk second, and only recommend a homemade buttermilk substitute (with milk + apple cider vinegar) as a last resort, since it doesn’t have the same thickness/richness.
• Eggs. Help bind the cake together. Pretty straightforward!
• Vanilla Extract enhances the deep chocolate flavor of this cake!
• Butter. This is how you get that classic flavor & fudgy texture! (I haven’t experimented with making this recipe dairy-free yet.) I use salted butter, but unsalted butter works, too!
• Cocoa Powder. I like my Texas sheet cake to taste good and chocolatey, so my secret is adding a *tiny* bit more cocoa powder than some other recipes do in both the gluten-free chocolate sheet cake & the fudgy frosting. It makes all the difference! Remember to use REGULAR unsweetened cocoa powder (like Ghiradelli or Hershey’s) here NOT Dutch-processed/dark cocoa powder (which won’t react properly with the baking soda).
• Hot Water. You’ll heat the water to almost boiling, which will dissolve the chocolate and butter, but the hot liquid will also help thin out the cake batter to a nice, pourable texture, which makes it easy to cover a whole sheet pan.
• Our Easy Fudge Frosting. Then, you’ll finish this gluten-free Texas sheet cake recipe with the classic chocolate fudge frosting made from butter, milk, cocoa powder, vanilla, and powdered sugar. Easy!

🌟 PRO TIP: If you’re going to make your gluten-free Texas sheet cake with pecans, I recommend toasting the pecans for extra flavor. It only takes a few minutes, but makes a BIG difference in taste!

How To Make Gluten-Free Chocolate Texas Sheet Cake, Step By Step

As always, you can find the full recipe, with ingredient amounts, detailed instructions, and tips in the recipe card below.

First, Make The Gluten-Free Texas Sheet Cake

1. Preheat The Oven & Prep Your Pans. Start by preheating the oven to 350 degrees and greasing a 13″ x 18″ x 1″ sheet pan with butter or spray oil (or line the pan neatly with parchment paper). 
2. Whisk Dry Ingredients. In a large mixing bowl, whisk gluten-free flour, sugar, baking soda, and salt until well combined. Set aside.
3. Mix Eggs, Sour Cream & Vanilla. In a large liquid measuring cup or small bowl, combine eggs, sour cream and vanilla. (There will be a second where this looks like a big mess–just keep whisking and it’ll come together smoothly.) 
4. Heat Butter, Cocoa Powder & Water. In a small saucepan, melt butter, cocoa powder, and water until almost simmering. You want it hot and smooth, so it can help thin out the batter. 
5. Assemble The Cake Batter. Add sour cream mixture to the flour mixture and mix to combine. (It’ll be thick almost like dough and a bit dry at this point.) Pour the cocoa mixture into the batter a bit at a time, mixing to incorporate the chocolate mixture before adding the next bit. Whisk until it’s smooth and even in texture.
6. Pour Into Prepared Pan. Pour the sheet cake batter onto your prepared baking sheet. Gently smooth out the batter into an even layer that goes all the way to the edges of the pan. (An offset spatula makes this easier)
7. Bake The Cake. Pop the cake pan into the oven and bake 18-20 minutes, or JUST until a toothpick inserted into the center of the cake comes out clean, with perhaps a few small moist crumbs. The cake is thin, so you don’t want to over-bake.)

Immediately Start The Chocolate Fudge Frosting

8. Right after you remove the cake from the oven, begin the frosting. (Unlike most cakes, you want to pour the frosting on while the cake is still warm.)
9. Melt Butter + Milk + Cocoa. In a large saucepan, melt butter, milk and cocoa powder together over medium heat, whisking regularly until it’s almost simmering/bubbling. (Don’t boil it, just heat it till it’s about to bubble.) 
10. Mix In Powdered Sugar & Vanilla. Remove the frosting from the heat and stir in powdered sugar and vanilla, whisking until there are not clumps of powdered sugar. There may be a few small air bubbles–this is totally fine, you just don’t want powdered sugar lumps. If you want to mix the pecans INTO the frosting, do that now. 
11. Pour Warm Frosting Over Warm Cake. Pour the fudge frosting over the still-warm sheet cake and quickly use an offset spatula to gently spread the frosting evenly over the surface. Be gentle, since the cake is pretty moist! If you want to sprinkle the cake with pecans, do that now. 
12. Cool At Least 20 Minutes. Let the sheet cake cool at least 20 minutes before slicing. I prefer to cool it about an hour to let the frosting set up, but some folks love when the frosting is still a bit soft and gooey.
13. Slice & Serve! When you’re ready, slice the cake into 24-36 slices. (For 24 slices, cut the whole cake into quarters, then cut each quarter into 6 slices. For 36 slices, cut the whole cake into quarters, then cut each quarter into 9 slices.)
14. Store Leftovers. If you have leftovers, cover the sheet pan with a lid or foil, and store at room temperature for 1-2 days, or the refrigerator for 2-3 days (my preference).