Baking School In-Depth: Swiss Cake Rolls

EGGS: Eggs bring richness through their yolks and moisture through their whites, but they also help leaven baked goods. This recipe uses three large eggs for the cake batter, adding leavening, flavor, richness, and structure, and egg whites are used to create stunning lift in the Swiss Meringue Buttercream.

GRANULATED SUGAR: The most common form of sugar, highly refined white sugar is made from sugarcane or sugar beets. The removal of molasses and impurities leaves the sugar white. When whipped with eggs, granulated sugar creates the airy leaven of our cake and adds the perfect touch of sweetness to our meringue buttercream and chocolate syrup.

VANILLA EXTRACT: A chocolate cake without vanilla lacks a beautiful depth of flavor. So, a dash of vanilla extract complements and enhances this cake’s rich cocoa notes. Vanilla also adds a lovely aroma to the Chocolate Syrup and buttercream.

ALL-PURPOSE FLOUR: All-purpose flour has a protein content of 10% to 12%, creating cakes that are tender yet have enough gluten structure to hold their rolled shape. This protein binds the cake batter and creates a base that withstands rolling, but it also ensures that the cake bakes up fluffy and light.

DUTCH PROCESS COCOA POWDER: Dutch process cocoa powder is treated with an alkaline solution of potassium carbonate to make it milder and less acidic in flavor and darker in color. For this recipe, we love Dutch process cocoa because it’s slightly less astringent in flavor than natural cocoa powder, so it makes an intense but not bitter-tasting chocolate cake.

KOSHER SALT: Our salt of choice, kosher salt is a pure, mined, additive-free salt that dissolves readily and has a crisp, clean taste. It’s flaked rather than granulated, which allows for more even distribution in the batter and buttercream.

NEUTRAL OIL: Oil incorporates like a dream into our chocolate cake batter, and because of its eternal liquid state, it keeps the cake moist and tender even as it cools. Neutral oils that are great for baking include vegetable, canola, grapeseed, and sunflower oil.

CREAM OF TARTAR: Cream of tartar aids in stabilizing the whipped egg whites in the buttercream, helping them hold their volume to reach impressive heights.

UNSALTED BUTTER: Butter is vital to the texture and richness of the Chocolate Ganache and the Swiss Meringue Buttercream, so choosing a European-style butter with a higher fat ratio than generic grocery store butter will yield the best results. Salt content can vary across butter brands, so we use unsalted butter to control the exact amount of salt in the recipe.

MAGICAL BAIN-MARIE

1. Preheat oven to 375°F (190°C). Spray a 141⁄2×91⁄2-inch rimmed baking sheet with baking spray with flour. Line bottom of pan with parchment paper; lightly spray parchment. A light mist of baking spray on the bottom of the pan makes parchment paper stick, preventing the paper from curling or shifting during baking.

2. In the heatproof bowl of a stand mixer, whisk together eggs, sugar, and vanilla by hand. Place bowl over a saucepan of simmering water. Cook, whisking occasionally, until an instant-read thermometer registers 110°F (43°C). We used the bain-marie method, a gentle heating of eggs and sugar over simmering water, to help the eggs whip up in dramatic fashion. Heating the eggs to just 110°F (43°C) allows proteins to denature, or unfold, and sets up the mixture to hold air more readily. Heating the sugar also means it will dissolve easily into the eggs.

3. Carefully return bowl to stand mixer. Using the whisk attachment, beat at high speed until thick, tripled in volume, and ribbon-consistency, 3 to 4 minutes. “Ribbon-consistency” is a common term used to describe the appearance of a batter or mixture. You will often find this term used for candy-making or in recipes for French macarons. The batter, when falling from the whisk attachment, creates a luxuriously thick ribbon. As the batter from the whisk settles atop the batter in the bowl, the edges of the “ribbon” should remain clearly defined on the surface for a moment before slowly disappearing. This ribbon stage tells us that we have whipped enough air into the batter to leaven the cake and are ready to move on to the next step.

EASY DOES IT

1. In a small bowl, sift together flour, 3 tablespoons (15 grams) cocoa, and salt. Using a large balloon whisk, gently fold flour mixture into egg mixture in two additions just until combined. Don’t be tempted to skip sifting. Clumps
can lead to deflated batter or a bite of something unpleasant due to trying to incorporate the lumps. A balloon whisk helps thoroughly incorporate the flour without disturbing the aeration. No balloon whisk? Use your stand mixer whisk attachment like a handheld whisk. It lacks a comfortable handle to hold but will work in a pinch.

2. Transfer 1 cup (112 grams) batter to another small bowl; whisk in oil until combined. Fold oil mixture into batter in two additions just until combined. Pour batter into prepared pan, and smooth flat with an offset spatula using as few strokes as possible. We first whisk the oil into a small portion of the batter to reduce any chance of overworking the entire mixture. You want to thoroughly incorporate the oil but keep a gentle touch. Every second spent overmixing deflates precious aeration. Stiff with aeration, sponge cakes do not spread or even out of their own accord in the oven, so smoothing the batter with an offset spatula is key for a level cake. Make sure to spread the batter to touch the sides of the pan and use as few strokes as possible to minimize deflation.

1. Bake until top looks dry and cake springs back when lightly pressed, 8 to 10 minutes. Immediately run a thin knife or a small offset spatula around edges of cake. Using a fine-mesh sieve, dust remaining 2 tablespoons (10 grams) cocoa all over cake. Invert cake onto a large cutting board covered with a clean kitchen towel. Carefully remove hot pan and parchment. When it comes to the dusting of cocoa, be generous. The cocoa will immediately begin absorbing moisture on the cake’s surface and will help the cake release from the kitchen towel after it has cooled.

2. Working quickly and starting at one short side of cake, cut cake in half lengthwise (do not separate cake pieces). Starting at one long side, immediately roll up half of cake and towel together. Starting at other long side, roll up other half of cake and towel together so both cake rolls meet in center of towel. Place seam side down, and gently press and roll cake roll so edges that meet are rounded. Transfer to a wire rack, and let cool completely, about 4 hours, or up to overnight. Since a rolled cake is most pliable when it’s hot, it’s imperative to begin rolling the cake right when it comes out of the oven.

BILLOWING BUTTERCREAM

1. In the heatproof bowl of a stand mixer, whisk together egg whites, sugar, salt, and cream of tartar by hand. Place bowl over a saucepan of simmering water. Cook, whisking constantly, until sugar dissolves and an instant-read thermometer registers 160°F (71°C).

2. Carefully return bowl to stand mixer. Using the whisk attachment, beat at high speed until white and fluffy, 5 to 6 minutes. Add butter, one piece at a time, beating until combined after each addition. (Mixture may look curdled at this point, but it will come together.) Beat at high speed for 3 minutes. Beat in vanilla. Use immediately, or refrigerate in an airtight container for up to 5 days. If refrigerated, let come to room temperature and re-whip in stand mixer until fluffy before using.

FILL AND ROLL

1. Carefully unroll cooled cakes. Brush liberally with Chocolate Syrup.

2. Transfer Swiss Meringue Buttercream to a pastry bag fitted with a 1⁄2-inch round piping tip (Ateco #807). Pipe buttercream onto cakes, leaving a 1⁄2-inch border along each long side that is bottom seam. Spread buttercream smooth with an offset spatula. Gently reroll cakes without towel, tucking tightly and making sure to create a small swirl but not pressing too hard.

3. Brush tops and sides of cake rolls with Chocolate Syrup. Place on wire rack or a baking sheet. Refrigerate until buttercream is firm and set, about 1 hour.

FINAL FLOURISH

1. In a medium heatproof bowl, place chocolate.

2. In a medium saucepan, heat cream and butter over medium heat, whisking frequently, just until steaming and bubbles form around sides of pan. (Do not boil.) Remove from heat; pour hot cream mixture over chocolate. Let stand for 5 minutes; whisk until chocolate is melted and mixture is smooth.

3. Trim 3⁄4 inch from each end of cake rolls, and cut each cake roll into 3-inch-long pieces. Place on wire rack, and pour warm Chocolate Ganache onto each cake roll to completely coat. Let stand at room temperature until set, 15 to 20 minutes. Serve immediately.