This Texas Sheet Cake recipe is THE ONE, you guys! As in, the only one you will ever need. Sour cream in the cake and the glaze, brown sugar, and extra cocoa make this the BEST chocolate sheet cake of your life!!
Preheat your oven to 350 degrees F. Line a jelly roll pan* with parchment paper, or spray well with nonstick spray.
Make the cake batter. In a medium or large saucepan, add 1 cup butter, 1 cup water, and 3/4 cup cocoa. Bring to a boil over medium high heat, sticking around to stir it. Once it boils, take it off the heat.
Let it cool for a minute or two, then stir in 1/4 cup vegetable oil, 1 cup brown sugar, 1 cup granulated sugar, and 2 teaspoons vanilla. Beat well with a whisk.
Add 2 cups flour, making sure to spoon the flour into the measuring cup and leveling it off. Add 3/4 teaspoon kosher salt (or sea salt) and 1 teaspoon baking soda. Use a small spoon to blend the salt and soda into the flour a little bit. Use a whisk to blend the dry ingredients into the batter thoroughly. Mix only until well combined and there are only a few lumps. (Don't over mix, or you will get a tough cake)
In a glass measuring cup, add 3/4 cup of sour cream. Add 2 eggs and beat well until combined.
Add the sour cream and eggs to the saucepan and fold the mixture in using a spatula, stirring only until it is just combined.
Pour the batter into the prepared pan and spread evenly to the sides.
Bake at 350 for about 17-20 minutes* (check times below), until a toothpick comes out of the center with no wet batter on it. The sides of the cake should just be starting to pull away from the edge of the pan. Don't over bake!
Meanwhile, make the frosting. Clean out the saucepan you used for the batter** and add 3/4 cup butter and mounded 1/2 cup cocoa. Stir together over medium heat until it comes to a boil, then remove from the heat.
Add 2 cups powdered sugar and whisk well.
Add 1/2 cup mounded sour cream and 2 teaspoons vanilla extract. Stir well.
Use a whisk to stir in the remaining and 1 and 1/2 cups powdered sugar, plus 1/4 teaspoon kosher or sea salt. Beat very well with the whisk. If you can't get all the powdered sugar lumps out, bust out your hand mixer and beat on high until it is smooth.
If your cake is not done baking (or still too hot) when you finish the glaze, stir the frosting every now and then to break up the hardened shell on top.
When the cake is done, take it out of the oven and let cool for 15-20 minutes. Spread the glaze over the cake, moving quickly, as it sets pretty fast. Let the frosting set up for at least 20-60 minutes before serving. (Or, you know. Don't.)
Serve this with milk. No, seriously.
The Jackie: my friend Jackie showed me her favorite way to eat this cake. Take two slices and stack them together so there is frosting in the middle and on top. Then stick it in the microwave. Whaaaat yes please it's so good you need to try it!!
Notes
*The size of your jelly roll pan is a matter of debate. You can make this cake in a 9x13 inch cake pan (thick cake), a 10x15 inch jelly roll pan (thinnish cake) or an 12x18 inch half baking sheet (thinnest cake). I prefer the 12x18. The first time I made it, I did it in a 10x15, and found myself only wanting to eat the top half of my slice of cake so that there was a higher ratio of frosting. (The photos of this cake is of one that was baked in a 10x15.) The 12x18 gives you the perfect ratio of cake to frosting in my opinion.If you are baking this in a 9x13 bake for 23-25 minutes. If you do a 10x15, bake for about 20 minutes. If you bake it in a 12x18, bake for about 18-20 minutes.All of these times are going to vary because everyone's oven is different.** I actually never do this. I just start making the frosting in the same pan without washing or even wiping it out. The danger is that the remaining batter up the sides of the pan that you couldn't scrape out all the way could scorch. I use the butter to rub the sides of the pan occasionally to avoid this. I can't even believe I added this note, probably washing the pan is easier! These are the kind of risks that make me feel like I'm living a dangerous life.