Preheat oven to 350°F. Line a jelly roll (10×15”) pan with foil and spray with cooking spray (I like to use the spray with flour).: You will notice the kitchen warming and a faint metallic smell as the oven comes up to 350°F , which sets the stage for an even bake. Preparing a jelly roll pan with foil and a flour containing spray ensures the delicate sponge releases cleanly; this step is crucial because any sticking will make rolling difficult. I always press the foil into the corners so the batter spreads evenly, and I also smooth the spray into a thin, even layer to avoid pooling. If you skip lining or spraying properly the cake may cling and tear during unrolling. A common mistake is preheating to the wrong temperature, so double check your oven dial and consider an oven thermometer for accuracy.
Beat eggs at high speed for 5 minutes, until frothy and dark yellow. Beat in sugar, lemon juice, and zest.: As you beat, the mixture transforms into a lively, frothy mass that smells faintly of fresh lemon and warmed egg. High speed whips in air creating volume, and you should see ribbons form when you lift the beater, signaling ready structure. When you add the sugar , it dissolves into the foam, giving a glossy sheen and a stable batter. The aroma of citrus becomes more pronounced after the lemon juice and zest are folded in, and that bright scent indicates a good balance of flavor. Underbeating here leads to a flat sponge and possible cracking, so resist the urge to move on early. If your mixture looks pale but not airy, keep beating in 30 second bursts until you get the right lift.
Whisk together salt, baking powder, and flour. Stir into wet ingredients just until blended.: The dry mix should be pale and evenly combined, smelling faintly of flour and a trace of chemical lift from the baking powder . When you fold the dry ingredients in, you will see the batter lose some of its gloss as the flour hydrates. The crucial sensory cue is a uniform, ribbonlike batter with no streaks of dry flour remaining. Stirring just until blended prevents gluten overdevelopment, which would make the sponge tougher and harder to roll. Avoid vigorous mixing, and if you overmix, you will notice a denser, less flexible batter and potential cracking later.
Spread in prepared pan. Batter will be in a very thin layer and you will need to use a wooden spoon or spatula to spread it to all the corners of the pan. Bake for 10-15 minutes (mine took 11).: As you spread the thin batter across the jelly roll pan , it should look even and glossy. The thinness helps the cake bake quickly and stay pliable. In the oven you will see the top set and turn a pale golden color, and the aroma will shift to a warm, baked note with citrus hints. Start checking around 10 minutes to avoid overbaking. Overbaking dries the sponge and makes it likely to crack during rolling. When done, the surface should spring back slightly to the touch and have a uniform, lightly golden color.
While the cake is baking, set a clean kitchen towel out on a large work surface. Sprinkle liberally with powdered sugar (about 1/4 cup). As soon as the cake comes out of the oven, turn it over on the kitchen towel sprinkled with powdered sugar. Remove foil carefully.: The towel preparation is tactile and a bit ritualistic; the powdered sugar creates a barrier that prevents sticking and adds a sweet note to the outer layer. When you invert the hot cake onto the towel, steam will rise and the cake surface will look glossy. Removing the foil must be done gently so the sponge does not tear. If the foil clings, use a thin knife edge between the foil and cake to help lift it off slowly. Not dusting enough powdered sugar is a common error that can lead to sticking and tearing during the next rolling step.
Working at the short end, fold the edge of the towel over the cake. Roll tightly, rolling up the cake into the towel. Let cool completely while rolled, at least one hour.: Rolling while hot allows the cake to form the memory of the spiral, which prevents cracking later. You will feel the warmth dissipate as it cools, and the towel will hold the shape. Letting it cool fully is critical because rolling a warm filled cake can cause the whipped cream to melt and the roll to lose definition. A common misstep is not rolling tightly enough, which creates large air pockets; aim for a snug roll that still has a gentle give.
While the cake is chilling, make the filling. Beat the heavy whipping cream and powdered sugar until stiff peaks form. Chill until ready to use.: Cold cream whips up into a creamy cloud, and you will hear a subtle change in the mixer sound as the texture transforms from liquid to soft and then to stiff peaks. The mixture should hold a peak that stands upright but still feels light, and the powdered sugar will melt gently into the cream, smoothing it and adding stability. If the cream is too warm it will not thicken properly, so keep everything chilled. Overbeating will turn the cream grainy and eventually into butter, so stop as soon as firm peaks appear.
When cake is cool, carefully unroll the towel. Spread the whipped cream over the cake. (You will have some whipped cream left over.) Sprinkle with chopped strawberries. Gently but tightly, re-roll the cake and wrap it in plastic wrap. Chill until it firms up a bit, at least one hour or overnight.: Unrolling reveals the delicate inner surface of the sponge, which should be slightly matte and soft. Spreading the whipped cream should feel silky under your spatula, and the chopped strawberries introduce juicy bursts that contrast the airy cream. Re rolling should be done with a steady hand; the log should be compact without squeezing out the filling. Wrapping and chilling lets the flavors meld and firms the shape for clean slicing. A frequent error is overfilling, which makes sealing the roll messy and causes leakage when slicing.
If desired, use the rest of the whipped cream to frost the outside. Garnish with berries.: Smearing a thin crumb coat of remaining whipped cream gives the roll a polished look and adds extra creaminess. The surface should be smooth and cool to the touch, and bright strawberries on top create an attractive contrast. Keep decorations minimal so the spiral remains the focal point. If you try to frost with warm cream it will slide off, so ensure the cake is well chilled first.
Slice and serve. Store in refrigerator. Once frosted with the whipped cream, it’s best served the same day. You can make the cake up to 2 days ahead.: Slicing reveals the spiral, and you should see defined layers of sponge, cream, and fruit. A serrated knife and gentle sawing motion help preserve the swirl. The cake tastes brightest the day it is frosted because whipped cream can soften over time, but storing covered in the refrigerator keeps it safe for up to 48 hours. Common mistakes include slicing with a dull knife, which squashes the roll, so use a sharp serrated blade for clean pieces.