Lemon Sunshine Cake Recipe

Prepare oven and pan

Preheat the oven to 350°F (175°C). Lightly grease and line an 8-inch round cake pan with parchment paper, leaving an overhang for easy removal.

Whisk dry ingredients: In a medium bowl, whisk together the all-purpose flour, baking powder, and salt until evenly combined.

Mix wet ingredients: In a separate large bowl, whisk the eggs with granulated sugar until slightly thickened and pale (about 1–2 minutes). Add the melted butter, milk, lemon zest, lemon juice, and vanilla extract; whisk until smooth.

Combine batter: Add the dry ingredients to the wet mixture and fold gently with a spatula until just combined. Do not overmix; a few small lumps are fine.

Bake: Pour the batter into the prepared pan, smooth the top, and bake for 20–25 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs. The cake should be lightly golden.

Cool: Let the cake cool in the pan for 10 minutes, then invert onto a wire rack and cool completely. Once cooled, slice the cake horizontally into two even layers using a serrated knife.

Make curd base: In a medium stainless-steel saucepan, whisk together the lemon juice, granulated sugar, eggs, lemon zest, and salt until smooth and fully combined.

Cook gently: Place the saucepan over medium-low heat and cook, stirring constantly with a heatproof spatula or whisk, until the mixture thickens enough to coat the back of a spoon, about 7–10 minutes. Do not let it boil vigorously to avoid curdling.

Finish curd: Remove from heat and immediately whisk in the cold cubed butter, a few pieces at a time, until fully melted and the curd is silky. Taste and strain through a fine-mesh sieve into a bowl to remove zest or cooked bits for an extra-smooth curd.

Chill: Cover the surface with plastic wrap to prevent a skin from forming and refrigerate until completely cool, at least 1 hour. The curd will thicken as it chills.

Chill equipment: Place the mixing bowl and whisk or beaters in the refrigerator or freezer for 10 minutes to chill — this helps the cream whip better.

Whip cream: Pour the cold heavy cream into the chilled bowl and whip on medium speed until soft peaks form.

Combine mascarpone: In a separate bowl, lightly loosen the mascarpone with the powdered sugar and vanilla until smooth (do not overbeat or it may become grainy).

Fold together: Gently fold the whipped cream into the mascarpone mixture in two additions until uniform and light. Fold in the teaspoon of lemon zest. Taste and adjust sweetness with a little more powdered sugar if desired.

Chill: Refrigerate the finished topping while you assemble the cake so it firms slightly, about 15–20 minutes.

Brush and layer: If the sponge is slightly dry, brush each cut surface lightly with the cooled simple syrup. Place the bottom cake layer on your serving plate.

Spread curd: Spoon about half of the chilled lemon curd over the bottom layer and spread evenly, leaving a small border at the edge to prevent it from oozing out.

Add top layer: Gently set the second cake layer on top, pressing very lightly to adhere. If using, warm the optional extra lemon curd briefly and drop small spoonfuls onto the whipped mascarpone for decorative swirls.

Top with mascarpone: Spread the whipped mascarpone evenly over the top and sides of the cake with an offset spatula. If you added extra curd, use a skewer to create light swirls.

Garnish: Decorate with fresh lemon slices or candied lemon peel and mint leaves as desired.

Chill thoroughly: Refrigerate the assembled cake, uncovered for 15 minutes then covered, for at least 3 hours or preferably overnight. The cake is served cold and the chilling allows flavors to meld and the curd to set.

Serve: Remove from refrigerator 5–10 minutes before slicing to ease cutting. Slice with a sharp knife dipped in hot water and wiped dry between cuts for clean slices.