Rub the lemon zest into the sugar

• Place the lemon zest and sugar in a large bowl.
• Rub them together thoroughly with your fingertips until the sugar is fragrant and moistened with the lemon oils.

Make the dry mixture

• Whisk the flour, baking powder, baking soda and salt into the lemon sugar.
• Add the cold cubed butter and break it up into the dry ingredients with your fingertips, as if making biscuits, until the mixture resembles coarse crumbs.

Finish the cake batter

• Whisk in the eggs, lemon juice, buttermilk and vanilla until the batter is smooth and just combined.

Bake the cake layers

• Divide the batter between the prepared cake pans.
• Bake at 180 °C until a skewer inserted in the center comes out clean.

Cool and split the layers

• Let the cakes cool completely in the pans, then turn out onto a cooling rack.
• Once fully cooled, slice each cake layer horizontally in half to make thin layers.

Make the cream cheese frosting

• Beat the softened cream cheese with the powdered sugar and vanilla until smooth.
• Whip in the cold heavy cream until light and fluffy.
• Stir a little turmeric powder into the portion of frosting used for the outside of the cake to give it a bright yellow color.

Assemble and decorate

• Stack the cake layers with a layer of frosting between each.
• Cover the cake with the yellow frosting and smooth it out.
• Pat the lemon slices thoroughly dry, then arrange them on top with the fresh thyme sprigs.