Whisk 1 whole egg and 2 egg yolks in a saucepan, then add 60g granulated sugar and mix until dissolved.

Grate the zest of 2 lemons and squeeze their juice (about 60g), whisking it into the egg mixture.

Cook over low heat for 7 minutes, stirring constantly, then add 30g butter and mix until melted.

Sift the mixture into a bowl and cover with plastic wrap to cool.

Preheat the oven to 170°C and prepare a 16 cm (6-inch) round cake pan with parchment paper.

Whisk 3 eggs, 80g sugar, and 1 tsp vanilla until combined, then warm over a saucepan with 1-2 inches of water until it reaches 40°C.

Melt 25g butter and 25g milk with lemon zest, then whisk the egg mixture on high speed for 6 minutes until it reaches the ribbon stage.

Sift in 90g cake flour in batches, folding gently, then add 7g poppy seeds and mix.

Fold in the butter-milk mixture and pour the lemon cake batter into the pan. Tap to remove air pockets and bake for 35-40 minutes.

Let the cake cool in the pan for a few minutes, then remove and cool completely on a wire rack.

Dissolve 12g sugar and 10g lemon juice in 75ml hot water, stir, and let it cool.

Beat until stiff peaks form, then transfer half into a piping bag for later use.

Slice the cooled cake into 3 even layers, each about 1.5 cm thick.

Brush the first layer with lemon syrup, spread with mascarpone cream, and smooth the surface. Pipe some cream around the edges and fill the center with lemon curd. Use a spatula to smooth it out.

Repeat for the second layer. For the third layer, brush with lemon syrup and crumb-coat the cake with the remaining mascarpone cream in the bag.

Cover the entire moist lemon cake with the remaining half of the cream in the bowl.

Chill the cake in the fridge for at least 3 hours, then spread the remaining lemon curd on top and garnish with lemon or lime zest and wedges.