Lime and Tamarind Cakes

STEP 1: MAKE THE TAMARIND JELLY

Sprinkle the gelatine over the cold water in a small bowl and leave it to bloom for 5 minutes. Warm the tamarind, water, sugar and salt in a small saucepan over medium heat, stirring until the sugar dissolves and the mixture is smooth and glossy; do not let it boil hard. If you are using wet paste, push the mixture through a fine sieve. Off the heat, stir in the bloomed gelatine until it has fully dissolved.

STEP 2: SET AND CUT THE JELLY DISCS

Line an 8-inch square pan with plastic wrap and pour in the jelly to a depth of about 1/4 inch. Refrigerate for at least 1 hour, until it is firm enough to cut cleanly. A jam-soft set lets the top layer slide, so the jelly needs to hold a cut edge. Stamp out 12 discs with a 1 1/2-inch cutter, slightly smaller than the sponge rounds will be, and keep them chilled on the lining until assembly.

STEP 3: MAKE THE COCONUT AND LIME SPONGE

Heat the oven to 350 degrees F. Line a 13 x 9-inch pan with parchment, leaving an overhang on the long sides. Whisk the flour, desiccated coconut, baking powder and salt together. Beat the butter and sugar until pale and light, 4 to 5 minutes, then add the eggs one at a time, beating well after each. Beat in the lime zest and vanilla. Fold in the dry ingredients in three additions, alternating with the coconut milk and lime juice and finishing with the dry. Do not overmix.

STEP 4: BAKE AND CHILL THE SHEET

Weigh the batter into the pan, spread it level with an offset spatula and tap the pan firmly on the counter twice. One even sheet is what makes twelve matching cakes possible. Bake for 25 to 30 minutes, until a skewer comes out clean and the sponge springs back. Cool in the pan for 10 minutes, lift out onto a rack and cool completely, then wrap the sheet and refrigerate for 30 minutes. Cold sponge cuts cleanly without compressing.

STEP 5: CUT THE ROUNDS

If the sheet has domed at all, level the whole surface once with a long serrated knife rather than trimming cakes individually. Stamp out 24 rounds with a 2-inch cutter, pressing straight down without twisting. Sort them into 12 matched pairs by thickness and set the flattest rounds aside for the tops.

STEP 6: MAKE THE LIME BUTTERCREAM

Beat the butter until very pale, about 3 minutes. Add the confectioners' sugar in two additions, beating until smooth. Beat in the lime zest, lime juice and salt. If the buttercream looks loose, chill it for 10 minutes and re-whip. Transfer it to a piping bag fitted with a small round tip.

STEP 7: ASSEMBLE THE CAKES

Pipe a closed ring of buttercream around the edge of each base round to make a dam; the jelly sits inside it and cannot spread outward under pressure. Set a tamarind jelly disc inside each ring and add a small dot of buttercream in the centre to grip the top layer. Place the matched top round on, pressing straight down with flat fingers rather than at an angle, and check each cake at eye level before the buttercream sets. Refrigerate the assembled cakes for 30 minutes.

STEP 8: MAKE THE COCONUT MARZIPAN

Grind the desiccated coconut fine in a food processor, then pulse it with the ground almonds and confectioners' sugar. Add the egg white, lime juice and almond extract and pulse to a firm, pliable paste, adding a teaspoon more egg white only if it will not come together.

STEP 9: TOP AND DECORATE

Roll the marzipan on a confectioners'-sugar-dusted surface to an even 1/8 inch, using rolling guides or two 1/8-inch strips of wood either side of the paste. Uneven marzipan reintroduces the fault the rest of the method removes. Stamp out 12 discs with the same 2-inch cutter. Brush each cake top with the barest film of warmed apricot jam or lime syrup and press a disc on, smoothing from the centre out. Colour a little fondant yellow and a little green, model 12 small spring flowers with a leaf each and set one on each cake.

STEP 10: SERVE

Bring the cakes to cool room temperature before serving, about 20 minutes out of the fridge. They are best on the day and will keep, boxed and chilled, for 2 days.