Chocolate sheet cake

This undated photo provided by America's Test Kitchen in November 2018 shows a chocolate sheet cake in Brookline, Mass. This recipe appears in the "Complete Cookbook for Young Chefs." (Carl Tremblay/America's Test Kitchen via AP)

Servings: 15

Start to finish: 1 hour, 15 minutes (Inactive time: 1 hour, plus cooling time)

Ingredients Needed:

Vegetable oil spray

1 1/2 cups sugar

1 1/4 cups all- purpose flour

1/2 teaspoon baking soda

1/2 teaspoon salt

1 1/3 cups bittersweet or semisweet chocolate chips

1 cup whole milk

3/4 cup Dutch-processed cocoa powder

2?3 cup vegetable oil

4 large eggs

1 teaspoon vanilla extract

Milk Chocolate Frosting (recipe follows)

Gather Cooking Equipment:

13-by-9-inch metal baking pan

Medium bowl

Whisk

Large saucepan

Rubber spatula

Toothpick

Oven mitts

Cooling rack

Icing spatula

Chef’s knife

Start Cooking!

Adjust oven rack to middle position and heat oven to 325 F. Spray bottom and sides of 13-by-9- inch metal baking pan with vegetable oil spray.

In medium bowl, whisk together sugar, flour, baking soda, and salt.

In large saucepan, combine chocolate chips, milk, and cocoa. Place saucepan over low heat and cook, whisking often, until chocolate chips are melted and mixture is smooth, about 5 minutes.

Turn off heat. Slide saucepan to cool burner and let mixture cool slightly, about 5 minutes.

Add oil, eggs, and vanilla to saucepan with chocolate mixture and whisk until smooth, about 30 seconds.

Add flour mixture and whisk until smooth, making sure to scrape corners of saucepan.

Use rubber spatula to scrape batter into greased baking pan and smooth top (ask an adult for help because saucepan will be heavy).

Place baking pan in oven. Bake until toothpick inserted in center comes out with few crumbs attached, 30 to 35 minutes.

Use oven mitts to remove baking pan from oven (ask an adult for help). Place baking pan on cooling rack and let cake cool completely in pan, about 2 hours.

Use icing spatula to spread frosting evenly over cooled cake (see photo, right). Cut cake into pieces and serve.

Milk Chocolate Frosting:

Makes about 2 Cups

Prep Time: 5 Minutes

Cook time: 10 minutes, plus 1 hour chilling time

This recipe calls for just three ingredients but they are transformed by the microwave and refrigerator. Don’t use salted butter in this recipe. This recipe makes enough to frost 12 cupcakes or one sheet cake.

Prepare ingredients:

11/3 cups milk chocolate chips

1/3 cup heavy cream

8 tablespoons unsalted butter, cut into 8 pieces and softened

Gather cooking equipment:

Large microwave-safe bowl

Rubber spatula

Whisk

Electric mixer

Start cooking:

In large microwave-safe bowl, combine chocolate and cream. Heat microwave at 50 percent power for 1 minute. Stop microwave and stir with rubber spatula. Heat in microwave at 50 percent power until melted, 1 to 2 minutes. Remove bowl from microwave.

Add softened butter to chocolate mixture and use whisk to stir and break up large butter pieces. Let sit until butter is fully melted, about 5 minutes. Whisk until completely smooth.

Refrigerate frosting until cooled and thickened, about 1 hour.

Use electric mixer to beat frosting on medium-high speed until frosting is light and fluffy, 30 seconds.

Nutrition information per serving: 456 calories; 253 calories from fat; 28 g fat (11 g saturated; 1 g trans fats); 86 mg cholesterol; 159 mg sodium; 45 g carbohydrate; 3 g fiber; 32 g sugar; 6 g protein.

For more recipes, cooking tips and ingredient and product reviews, visit https://www.americastestkitchen.com. Find more recipes like Chocolate Sheet Cake in “Complete Cookbook for Young Chefs .”

America’s Test Kitchen provided this article to The Associated Press.