America's Test Kitchen  is a real 2,500 square foot test kitchen located just outside of Boston that is home to more than three dozen full¬time cooks and product testers. Our mission is simple: to develop the absolute best recipes for all of your favorite foods. To do this, we test each recipe 30, 40, sometimes as many as 70 times, until we arrive at the combination of ingredients, technique, temperature, cooking time, and equipment that yields the best, most foolproof recipe. America’s Test Kitchen's online cooking school is based on nearly 20 years of test kitchen work in our own facility, on the recipes created for Cook's Illustrated magazine, and on our two public television cooking shows.

It’s finally here: graduation season. After thinking, writing, calculating, experimenting, reading, and exam-ing for years on end, students are finally donning robes, tossing their tasseled hats in the air, and marching across the stage to receive diplomas.

Such momentous occasions deserve momentous cakes: Layered desserts with rich frosting and the perfect spongy crumb.

But what if your graduate can’t eat gluten? They should still be able to have their celebratory cake and eat it, too. Which is why, in "The How Can It Be Gluten Free Cookbook" we came up with a recipe for a layer cake that’s moist, springy, and holds its own with a decadent, chocolate frosting.

A good yellow layer cake should melt in your mouth and taste of butter and vanilla. Unfortunately, many of the gluten-free layer cake recipes we tried were terribly greasy, because the standard amount of butter in a traditional yellow layer cake (two sticks) was way too much. After attempting many different ways to keep the cake moist while still cutting down on butter, we found the secret ingredient: melted white chocolate. It worked like a charm, boosting richness without making the cake greasy.

Congratulations to all the graduates this spring, and may your next steps be as sweet as this cake.

View the slideshow for an step-by-step tutorial on mixing the batter.

Yellow Layer Cake
(Serves 10 to 12)

6 ounces white chocolate, chopped
8 tablespoons unsalted butter, cut into 8 pieces
11 ounces (1 3⁄4 cups plus 2⁄3 cup) ATK Gluten-Free Flour Blend
1 tablespoon baking powder
1 1⁄4 teaspoons xanthan gum
1 teaspoon salt
1⁄4 teaspoon baking soda
4 large eggs, separated
Pinch cream of tartar
7 ounces (1 cup) sugar
1 1⁄2 tablespoons vanilla extract
2⁄3 cup sour cream
4 cups frosting

1. Adjust oven rack to middle position and heat oven to 325 degrees. Grease two 9-inch round cake pans, line bottoms with parchment paper and grease parchment.

2. Microwave chocolate and butter together in bowl at 50% power, stirring occasionally, until melted, about 2 minutes. Whisk mixture until smooth, then set aside to cool slightly. In separate bowl, whisk flour blend, baking powder, xanthan gum, salt and baking soda until combined.

3. Using a stand mixer fitted with a whisk, whip egg whites and cream of tartar on medium-low speed until foamy, about 1 minute. Increase speed to medium-high and whip whites to soft, billowy mounds, about 1 minute. Gradually add 1⁄2 cup sugar and whip until glossy, stiff peaks form, 2 to 3 minutes; transfer to a separate bowl.

4. Return now-empty bowl to mixer, add egg yolks and vanilla, and whip on medium speed until well blended, about 30 seconds. Gradually add remaining 1⁄2 cup sugar, increase mixer speed to high, and whip until very thick and pale yellow, about 2 minutes. Reduce mixer speed to medium, add chocolate mixture and sour cream, and whip until combined, about 30 seconds. Reduce speed to low, slowly add flour blend mixture, and mix until thoroughly combined, about 1 minute.

5. Using a rubber spatula, stir 1/3 of whipped egg whites into batter to lighten. Gently fold in remaining whites until no white streaks remain. Divide batter evenly between prepared pans and smooth tops. Bake until cakes begin to pull away from sides of pans and spring back when pressed lightly, 30 to 32 minutes, switching and rotating pans halfway through baking.

6. Let cakes cool in pans on wire rack for 10 minutes. Run knife around edge of cakes to loosen. Remove cakes from pans, discard parchment, and let cool completely on rack, about 1 1⁄2 hours. (Cake layers can be wrapped tightly in plastic wrap and stored at room temperature for up to 1 day.)

7. Place 1 cake layer on platter and spread 1 1⁄2 cups frosting evenly over top using a small icing spatula or butter knife. Top with second cake layer, press lightly to adhere, then spread remaining 2 1⁄2 cups frosting evenly over top and sides. Serve.

Creamy Chocolate Frosting
(Makes 4 cups)

This not-too-sweet frosting relies on egg whites and sugar heated over a double boiler until thickened and foamy. Knobs of softened butter are then added, and the mixture is beaten until silky and light. Cool the chocolate to between 85 and 100 degrees before adding it as the final step in this recipe.

4 2⁄3 ounces (2⁄3 cup) sugar
4 large egg whites
Pinch salt
24 tablespoons (3 sticks) unsalted butter, cut into 24 pieces and softened
12 ounces bittersweet chocolate, melted and cooled
1 teaspoon vanilla extract

1. Combine sugar, egg whites, and salt in bowl of stand mixer; place bowl over pan of simmering water. Whisking gently but constantly, heat mixture until slightly thickened and foamy and it registers 150 degrees, 2 to 3 minutes.

2. Place bowl in a stand mixer fitted with a whisk attachment. Beat mixture on medium speed until it has consistency of shaving cream and has cooled slightly, about 5 minutes. Add butter, 1 piece at a time, until smooth and creamy. (Frosting may look curdled after half of butter has been added; it will smooth out with additional butter.)

3. Once all butter is added, add cooled melted chocolate and vanilla and mix until combined. Increase speed to medium-high and beat until light and fluffy, about 30 seconds, scraping beater and sides of bowl with a rubber spatula as necessary. If frosting seems too soft after adding chocolate, chill it briefly in refrigerator, then rewhip until creamy.

More from America's Test Kitchen:
Read additional gluten-free posts and learn more about the book at HowCanItBeGlutenFree.com
Our Online Cooking School course on gluten-free baking
Our favorite round cake pan

Previously:
Perfect chocolate chip cookies (that happen to be gluten-free)
Five tips for gluten-free cookies
What do "gluten," "celiac" and "sensitivity" mean?
Allergy-friendly grocery shopping without breaking the bank
Five places you won't miss the gluten
Gluten-free cooking ingredients