Place the sugar and zest in a small bowl. Use your fingers to rub the mixture together until the zest is evenly distributed and the mixture is fragrant.

Pour the sugar into a medium sized saucepan then add in the eggs and orange juice. Whisk until evenly combined. Set the saucepan over medium heat and cook, whisking constantly until the sugar has dissolved, 3 minutes.

Reduce the heat to medium-low and gradually add in the butter, a tablespoon at a time over the course of the next 5 minutes, whisking constantly until smooth and incorporated.

Continue to whisk, for 6 more minutes, or until the mixture is thick enough to coat the back of a spoon. Remove from the heat.

Set up a timer to count down 6 minutes. Then, use a hand-held immersion blender or stand blender to blitz the mixture for the total of the time.

Strain the curd into a sealable container and cover the surface closely with plastic wrap. Chill until very cold before use, preferably overnight.

Pre-heat the oven to 180 c (350 f). Grease and line three x 15 cm (6 inch) cake tins with parchment paper. Set aside.

Place the butter and sugar in the bowl of a stand mixer fitted with the beater attachment. Mix, on medium speed until light and fluffy, 4 to 5 minutes.

Add in the eggs, one at a time, until evenly incorporated and the batter is fluffy, 3 more minutes.

Whisk together the cake flour, almond meal, baking powder, ground cardamom and salt. Set the bowl aside.

Place the sour cream, orange juice, zest, orange blossom water, vanilla bean and almond extract into a large mixing jug. Stir to combine well.

Pour a third of the sour cream mixture into the beating batter. Beat until just combined then add in a third of the dry flour ingredients. Continue to alternate the additions until all of the sour cream mixture and dry ingredients have been used up.

Increase the mixer speed to medium-high and beat until well combined, 2 to 3 minutes.

Divide the cake batter between the prepared cake pans and use a rubber spatula to smooth out the tops. Bake, for 35 to 45 minutes, or until the cakes are golden brown and a skewer inserted into the middle comes out clean.

Let the cakes cool in their pans for 15 minutes before turning out and onto a wire rack to let cool completely.

Once cool, level off any domed tops with a large serrated knife or cake leveller.

Place the egg whites and sugar into the bowl of a stand mixer. Whisk by hand to combine.

Place the bowl over a saucepan of barely simmering water set on medium-low heat. Heat, whisking often, until the mixture reaches a temperature of 70 c (160 f) on a candy thermometer.

Once at temperature, remove the bowl from the heat and set it on the base of a stand mixer fitted with the whisk attachment. Whisk, on medium-high speed, for 8 to 10 minutes, or until the mixture holds stiff peaks.

Pause mixing and swap the whisk attachment for the beater attachment. Add in the butter, a tablespoon at a time, until it is all incorporated. Add in the mascarpone and orange blossom water.

Increase the mixer speed to high and continue to beat until the buttercream is thick and silky smooth, 5 more minutes.

Place the light brown sugar, unsalted butter and heavy cream in a medium sized saucepan set over medium-low heat. Stir constantly with a wooden spoon until the butter and sugar have melted.

Increase the heat to medium and let the mixture come to a light rolling boil, swirling the pan occasionally but not stirring. Let the mixture continue to boil, until it has reduced by half, about 15 minutes.

Remove from the heat and stir in the orange blossom water and salt. Set aside until completely cooled to room temperature before pouring over the cake.

Place the orange curd and a few tablespoons of the mascarpone swiss meringue buttercream into two separate piping bags fitted with large tips. Set aside.

Place the first cake layer, cut side facing up, on a cake stand or serving platter. Pipe a ring of buttercream around the edges of the cake to form a buttercream ‘dam’. Then, fill the middle of the ring with a piping of the orange curd.

Top with the second cake layer, cut side facing down, and again, pipe a second ring of buttercream around the edges of the cake then fill the center with the orange curd.

Finish with the remaining third cake layer, cut side facing down. Use an offset spatula to spread a thin layer of the buttercream over the top and sides of the cake to crumb coat it.

Set the cake in the refrigerator to harden the first buttercream layer, about 30 minutes.

Once set, remove the cake from the refrigerator and spread a generous amount of the buttercream over the entire cake to cover it.

Set the cake back in the refrigerator to set the buttercream, about 30 more minutes.

Remove the cake from the refrigerator and pour the cooled salted caramel directly over the top of the cake, using an offset spatula or butter knife to help spread it down the sides of the cake to form a dripping effect.

Set the cake back in the refrigerator to set the salted caramel until firm, 20 to 30 more minutes.

Once set, decorate the cake with some fresh, pesticide free flowers (if desired) and a sprinkling of flaky sea salt before serving.