This moist Pumpkin Sheet Cake with Brown Sugar Icing is an easy dessert for fall gatherings, Halloween parties or Thanksgiving. It starts with a boxed spice cake mix and bakes in a rimmed sheet pan, making it simple to prepare and easy to serve to a crowd. The homemade brown sugar icing makes it look like you put in considerably more effort than you did. We’ll keep that between us.

A piece of Pumpkin Sheet Cake on a plate with the sheet pan in the background.

Prep Time: 10 minutes
Bake Time: 15–17 minutes
Servings: 18-22

Cake Ingredients

15.25 ox Spice Cake Mix
½ cup of pumpkin puree
2 cups of whole milk

Icing Ingredients

½ cup of butter
1 cup of brown sugar
¼ cup of whole milk
2 cups confectioners sugar
¼ tsp vanilla extract

Ingredients: milk, spice cake mix, vanilla extract, pumpkin puree, confectioners' sugar, stick of butter and brown sugar on the counter.”

Get the full printable instructions with measurements at the bottom of the post in the recipe card.

Step 1: Preheat the oven to 350°F. Grease an 18-by-13-inch rimmed baking sheet with cooking spray or butter.

Step 2: Add the cake mix, pumpkin purée and milk to a large mixing bowl. Beat with an electric hand mixer for 60–90 seconds, or until evenly combined.

Step 3: Spread the batter evenly in the prepared pan. Bake for 15–17 minutes, or until a toothpick inserted into the center comes out clean. Place the pan on a wire rack and allow the cake to cool completely.

Step 4: While the cake is cooling, melt the butter in a saucepan over medium heat. Whisk in the brown sugar and bring the mixture to a boil. Boil for 1 minute, then remove the pan from the heat and whisk in the milk.

Step 5: Pour the mixture into a large heatproof bowl and allow it to cool completely.

Step 6: Beat in the confectioners’ sugar, 1 cup at a time. Add the vanilla extract and continue beating until the icing is smooth.

Step 7: Spread the icing evenly over the completely cooled cake. Cut into 18–22 pieces and serve.

Adding confectioners' sugar to the cooled butter, brown sugar and milk also added to a large mixing bowl

Whipped finished brown sugar icing in a large mixing bowl

Icing being spread on cake in a rimmed baking sheet

Caution: The cake and baking sheet will be hot when removed from the oven.

finished Pumpkin sheet cake with brown sugar icing

🍋 Simply Made Suggestions

Be sure to use plain pumpkin purée, not pumpkin pie filling, which already contains sugar and spices.
Let the cake cool completely before adding the icing. Allow the brown sugar mixture to cool before beating in the confectioners’ sugar.
Use an 18-by-13-inch rimmed sheet pan. A different pan size will change the cake’s thickness and baking time.
Begin checking the cake after 15 minutes. It’s finished when a toothpick inserted into the center comes out clean.

🧊 Leftovers

Cover the cake or transfer it to an airtight container. Store it in the refrigerator for up to 4 days.

🎃 Before You Go…

If this Pumpkin Sheet Cake with Brown Sugar Icing has you firmly in pumpkin mode, we’ve got plenty more where that came from. Browse our easy pumpkin recipes for cakes, muffins, breakfasts and plenty of other ways to put that can of pumpkin to work.

Pumpkin Sheet Cake with Brown Sugar Icing

sheet cake of pumpkin cake with brown sugar icing.

This easy pumpkin sheet cake starts with spice cake mix and canned pumpkin, then gets topped with homemade brown sugar icing. Baked in an 18×13-inch sheet pan, it's an easy fall dessert for feeding a crowd.

Tara

Prep Time 5

Cook Time 22

Total Time 27

Servings people

Equipment

18×13-inch rimmed sheet pan
electric hand mixer
measuring cups
mixing bowls

Ingredients

Cake ingredients

15.25 oz package Spice Cake Mix
1/2 cup pumpkin puree
2 cups milk

Icing ingredients

1/2 cup butter
1 cup brown sugar
1/4 cup milk
2 cups confectioners sugar
1/2 tsp vanilla extract

Instructions

Preheat the oven to 350°F. Grease an 18-by-13-inch rimmed baking sheet with cooking spray or butter.
Add the cake mix, pumpkin purée and milk to a large mixing bowl. Beat with an electric hand mixer for 60–90 seconds, or until evenly combined.
Spread the batter evenly in the prepared pan. Bake for 15–17 minutes, or until a toothpick inserted into the center comes out clean. Place the pan on a wire rack and allow the cake to cool completely.
While the cake is cooling, melt the butter in a saucepan over medium heat. Whisk in the brown sugar and bring the mixture to a boil. Boil for 1 minute, then remove the pan from the heat and whisk in the milk.
Pour the mixture into a large heatproof bowl and allow it to cool completely.
Beat in the confectioners’ sugar, 1 cup at a time. Add the vanilla extract and continue beating until the icing is smooth.
Spread the icing evenly over the completely cooled cake. Cut into 18–22 pieces and serve.