Raspberry Champagne Sheet Cake Recipe

<ul class="ingredients-main-list"><li class="ingredients-single-item">For the Champagne Cake:</li><li class="ingredients-single-item">340g unsalted butter, at room temperature</li><li class="ingredients-single-item">400g granulated sugar</li><li class="ingredients-single-item">5 large eggs, at room temperature</li><li class="ingredients-single-item">2 tsp vanilla extract</li><li class="ingredients-single-item">375g all-purpose flour</li><li class="ingredients-single-item">2 1/2 tsp baking powder</li><li class="ingredients-single-item">1/2 tsp salt</li><li class="ingredients-single-item">240ml champagne (or sparkling wine), at room temperature</li><li class="ingredients-single-item">For the Raspberry Filling:</li><li class="ingredients-single-item">300g fresh raspberries (frozen can work too)</li><li class="ingredients-single-item">100g granulated sugar</li><li class="ingredients-single-item">2 tbsp cornstarch</li><li class="ingredients-single-item">2 tbsp water</li><li class="ingredients-single-item">1 tbsp lemon juice</li><li class="ingredients-single-item">For the Champagne Buttercream:</li><li class="ingredients-single-item">340g unsalted butter, at room temperature</li><li class="ingredients-single-item">600g powdered sugar, sifted</li><li class="ingredients-single-item">3 tbsp champagne reduction (from 120ml champagne)</li><li class="ingredients-single-item">1/4 tsp salt</li><li class="ingredients-single-item">Few drops of pink food coloring (optional)</li><li class="ingredients-single-item">Fresh raspberries and edible gold leaf for decoration (optional)</li></ul>

<ul class="equipment-main-list"><li class="equipment-single-item">33x23cm (13x9-inch) cake pan</li><li class="equipment-single-item">Stand mixer or electric hand mixer</li><li class="equipment-single-item">Offset spatula</li><li class="equipment-single-item">Small saucepan for reductions</li><li class="equipment-single-item">Fine-mesh sieve</li></ul>

<ol class="no-list-style"><li class="MethodStepper"><h4 class="step-title">Step 1</h4>Preheat your oven to 175°C (350°F). Grease your 33x23cm (13x9-inch) cake pan and line with parchment paper, leaving some overhang on the sides for easy removal. Make sure your butter, eggs, and champagne are at room temperature – this is crucial for achieving a smooth, well-incorporated batter that will rise evenly.</li><li class="MethodStepper"><h4 class="step-title">Step 2</h4>For the champagne reduction (used in the buttercream): In a small saucepan, bring 120ml champagne to a simmer over medium heat. Allow it to reduce to about 3 tablespoons (this concentrates the flavor while cooking off most of the alcohol). Set aside to cool completely before using in the frosting.</li><li class="MethodStepper"><h4 class="step-title">Step 3</h4>In a medium bowl, whisk together the flour, baking powder, and salt. This pre-mixing ensures these dry ingredients are evenly distributed throughout the batter, preventing any pockets of baking powder that could create bitter spots in your finished cake.</li><li class="MethodStepper"><h4 class="step-title">Step 4</h4>In the bowl of your stand mixer fitted with the paddle attachment (or using an electric hand mixer), beat the butter on medium speed until creamy, about 1 minute. Add the sugar and cream together until light and fluffy, about 4-5 minutes. This extended creaming process creates tiny air bubbles that help your cake rise and achieve a tender crumb.</li><li class="MethodStepper"><h4 class="step-title">Step 5</h4>Add the eggs one at a time, beating well after each addition and scraping down the sides of the bowl as needed. Mix in the vanilla extract. The mixture might look slightly curdled at this stage – that's normal and will smooth out when you add the dry ingredients.</li><li class="MethodStepper"><h4 class="step-title">Step 6</h4>Gradually add the dry ingredients to the butter mixture in three additions, alternating with the room temperature champagne (beginning and ending with flour mixture). Mix on low speed just until combined after each addition. Be careful not to overmix as this develops gluten and can make your cake tough rather than tender.</li><li class="MethodStepper"><h4 class="step-title">Step 7</h4>Pour the batter into your prepared pan, smoothing the top with an offset spatula. Tap the pan gently on the counter a few times to release any large air bubbles. Bake for 28-32 minutes, or until a toothpick inserted in the center comes out clean and the top springs back when lightly touched. The cake should pull slightly away from the sides of the pan.</li><li class="MethodStepper"><h4 class="step-title">Step 8</h4>Allow the cake to cool in the pan for 15 minutes before using the parchment overhang to carefully lift it out onto a cooling rack. Let it cool completely before filling and frosting. A warm cake will melt your buttercream and cause the filling to run.</li><li class="MethodStepper"><h4 class="step-title">Step 9</h4>While the cake is cooling, prepare the raspberry filling. In a medium saucepan, combine the raspberries and sugar. Cook over medium heat, stirring occasionally, until the berries break down and release their juices, about 5-7 minutes. In a small bowl, whisk together the cornstarch and water to create a slurry, then add to the raspberry mixture along with the lemon juice. Continue cooking, stirring constantly, until the mixture thickens, about 2-3 minutes. Remove from heat and strain through a fine-mesh sieve to remove seeds (if desired). Allow to cool completely before using.</li><li class="MethodStepper"><h4 class="step-title">Step 10</h4>For the champagne buttercream, beat the butter in a stand mixer fitted with the paddle attachment on medium speed until creamy and light, about 3-4 minutes. Gradually add the sifted powdered sugar, mixing on low speed until incorporated, then increasing to medium-high to whip until fluffy. Add the cooled champagne reduction and salt, beating until well combined. If using, add a few drops of pink food coloring and mix until you achieve the desired shade.</li><li class="MethodStepper"><h4 class="step-title">Step 11</h4>Once the cake is completely cool, use a long serrated knife to carefully slice it horizontally into two even layers. Place the bottom layer on your serving plate. Spread the raspberry filling evenly over the bottom layer, leaving a small border around the edges to prevent it from oozing out. Gently place the top cake layer over the filling.</li><li class="MethodStepper"><h4 class="step-title">Step 12</h4>Frost the top and sides of the cake with the champagne buttercream using an offset spatula. You can create decorative swirls on top if desired. For an elegant finishing touch, garnish with fresh raspberries and small pieces of edible gold leaf. Refrigerate the cake for at least 30 minutes to set the frosting before serving.</li><li class="MethodStepper"><h4 class="step-title">Step 13</h4>For the best flavor, remove the cake from the refrigerator about 30 minutes before serving to allow it to come to room temperature. This cake will keep well in the refrigerator for up to 3 days, though the fresh raspberries on top are best added just before serving.</li></ol>