Why You’ll Love This Recipe

• Incredibly moist crumb thanks to a secret ingredient!
• Unique, subtle flavor from real Dr Pepper soda.
• Quick and easy pour-over fudge frosting.
• Perfectly feeds a crowd, baked in one sheet pan.

Equipment You’ll Need

• 10×15-inch jelly roll pan (or similar sheet pan)
• Medium saucepan
• Large mixing bowl
• Whisk
• Electric hand mixer (optional, but helpful for frosting)
• Measuring cups and spoons
• Rubber spatula

Ingredients

• For the Chocolate Cake:
• 2 cups all-purpose flour
• 2 cups granulated sugar
• 1 cup Dr Pepper
• 1/2 cup unsalted butter, cut into pieces
• 1/2 cup vegetable oil
• 4 tablespoons unsweetened cocoa powder
• 1/2 cup buttermilk, at room temperature
• 2 large eggs, lightly beaten, at room temperature
• 1 teaspoon baking soda
• 1 teaspoon vanilla extract
• 1/2 teaspoon salt
• 1 1/2 cups mini marshmallows
• For the Fudgy Dr Pepper Frosting:
• 1/2 cup unsalted butter, cut into pieces
• 1/4 cup Dr Pepper
• 3 tablespoons unsweetened cocoa powder
• 1 pound powdered sugar (about 3 1/2 to 4 cups), sifted
• 1 teaspoon vanilla extract
• 1 cup chopped pecans, toasted (optional)

Instructions

1. Preheat and Prep: Preheat your oven to 350°F (175°C). Lightly grease and flour a 10×15-inch jelly roll pan or line with parchment paper. Set aside.
2. Start the Chocolate Base: In a medium saucepan, combine 1 cup of Dr Pepper, 1/2 cup of butter, 1/2 cup of vegetable oil, and 4 tablespoons of cocoa powder. Bring the mixture to a rolling boil over medium heat, whisking occasionally until the butter is fully melted and everything is well combined. Once it boils, remove it from the heat.
3. Combine Dry Ingredients: In a large mixing bowl, whisk together the 2 cups of all-purpose flour and 2 cups of granulated sugar. Pour the hot Dr Pepper mixture directly into the flour and sugar mixture. Whisk until just combined – be careful not to overmix.
4. Add Remaining Wet Ingredients: In a separate small bowl, whisk together the buttermilk, beaten eggs, baking soda, vanilla extract, and salt. Pour this mixture into the chocolate batter and whisk until everything is smooth and incorporated. The batter will be thin, which is exactly what you want!
5. Fold in the Secret Ingredient: Gently fold the mini marshmallows into the cake batter using a rubber spatula. They will melt during baking, creating an unbelievably moist and tender texture.
6. Bake the Cake: Pour the batter into your prepared sheet pan and spread it into an even layer. Bake for 20-25 minutes, or until a wooden skewer inserted into the center comes out with moist crumbs attached. Be careful not to overbake.
7. Make the Frosting: While the cake is baking (about 10 minutes before it’s done), start the frosting. In the same saucepan (no need to wash it!), combine 1/2 cup of butter, 1/4 cup of Dr Pepper, and 3 tablespoons of cocoa powder. Bring this mixture to a boil over medium heat, whisking constantly.
8. Finish the Frosting: Once boiling, remove the pan from the heat. Immediately whisk in the sifted powdered sugar and vanilla extract until the frosting is smooth and glossy. If you’re using them, stir in the toasted pecans.
9. Frost the Warm Cake: As soon as the cake comes out of the oven, pour the warm frosting all over the top. Use an offset spatula or the back of a spoon to gently spread it to the edges. The heat from the cake will help the frosting glide on smoothly and set into a perfect, fudgy layer.
10. Cool and Serve: Let the cake cool in the pan for at least 30 minutes before slicing and serving. This allows the frosting to set properly. Enjoy the richest, most delicious cake ever!

Expert Cooking Tips

• Room Temperature is Key: Using room temperature buttermilk and eggs helps the batter come together smoothly, resulting in a more tender and evenly baked cake.
• Don’t Overmix the Batter: Once you combine the wet and dry ingredients, mix only until they are just incorporated. Overmixing develops the gluten in the flour, which can lead to a tough, dense cake.
• The Warm Frosting Trick: The magic of a Texas sheet cake is pouring the warm frosting over the warm cake. This allows a small amount of the frosting to seep into the top layer of the cake, making it extra fudgy and delicious while creating a signature crackly top once it cools.
• Toast Your Pecans: If using pecans, don’t skip toasting them! It only takes a few minutes in a dry skillet over medium heat, but it deepens their nutty flavor and adds a fantastic crunch that contrasts beautifully with the soft cake.

Substitutions and Variations

For a buttermilk substitute, you can use 1/2 cup of regular milk mixed with 1/2 tablespoon of lemon juice or white vinegar; let it sit for 5 minutes before using. If you don’t have Dr Pepper, Coca-Cola or Cherry Coke can be used, though the final flavor will be slightly different. For a nut-free version, simply omit the pecans from the frosting. You can try a 1-to-1 gluten-free baking flour blend, but be aware that the texture may vary slightly.

Common Mistakes to Avoid

The biggest mistake is overbaking the cake. A sheet cake bakes quickly, so start checking it at the 20-minute mark. Overbaking will result in a dry cake, which would be a tragedy! Another common error is letting the cake or the frosting cool down too much before combining them. The ‘warm-on-warm’ technique is essential for the signature texture of the frosting. Finally, be sure to sift your powdered sugar for the frosting to avoid any unpleasant lumps and ensure a silky-smooth finish.

Serving Suggestions

This cake is absolutely divine on its own, but to take it over the top, serve a warm slice with a generous scoop of vanilla bean ice cream. The contrast of the warm, fudgy cake and the cold, creamy ice cream is pure bliss. A simple dollop of fresh whipped cream or a drizzle of salted caramel sauce also pairs beautifully. And of course, what better to wash it down with than an ice-cold glass of Dr Pepper?

Storage and Reheating Tips

Store any leftover cake tightly covered right in the pan at room temperature for up to 3 days. If you need to store it longer, it will keep well in the refrigerator for up to a week. The cake can also be frozen; you can freeze the entire pan (well-wrapped in plastic wrap and foil) or individual slices for up to 3 months. Thaw at room temperature before enjoying.

Frequently Asked Questions

Can I really taste the Dr Pepper in the cake?

You won’t get a strong, fizzy soda taste. Instead, the Dr Pepper adds a wonderful depth and a subtle, hard-to-place flavor with notes of cherry, vanilla, and caramel that perfectly complements the rich chocolate.

Why do you add mini marshmallows to the cake batter?

This is a fantastic little trick! The mini marshmallows melt completely into the batter as it bakes, creating little pockets of moisture and sweetness. This results in an exceptionally moist, tender, and slightly chewy crumb that stays fresh for days.

Can I make this recipe in a 9×13-inch pan instead?

Yes, you absolutely can! The cake will be thicker, so you’ll need to adjust the baking time. Start checking for doneness around 30-35 minutes. The frosting amount will be perfect for a thicker, more decadent layer on top.

My frosting seems too thin/thick. How can I fix it?

The frosting consistency can be easily adjusted. If it seems too thin, let it cool for a few minutes to thicken up, or add a little more sifted powdered sugar. If it’s too thick to pour, simply whisk in another tablespoon of Dr Pepper or milk until it reaches a smooth, pourable consistency.

Conclusion

There you have it – a truly special chocolate cake that’s guaranteed to have everyone asking for the recipe. It’s the perfect treat for potlucks, birthdays, or just a Tuesday night when you need a little something sweet. I can’t wait for you to try it and experience the magic of Dr Pepper cake for yourself! If you make it, please snap a photo and share it on Pinterest or Instagram—I would absolutely love to see your creation!