Preheat the oven to 180°C/350ºF/gas 4. Grease two 20cm springform cake tins with a little butter, line the bases with greaseproof paper, then dust lightly with flour.
Beat the butter and sugar together until very light and fluffy. Add the eggs one by one, making sure you beat each one in well before you add the next, then fold in the flour, food colouring and zest from 1 lemon. Add a splash of milk to loosen, if needed. Divide between the prepared cake tins, spreading it out well with a spatula, then place in the hot oven for 20 to 25 minutes, or until golden and an inserted skewer comes out clean. Allow to cool slightly, then carefully turn out onto a baking rack to cool completely.
Meanwhile, to make the icing, sift the icing sugar into a large bowl, add the butter and beat until pale and creamy. Halve the vanilla pod lengthways, scrape out the seeds and add them to the bowl. Add the cream cheese, finely grate in the zest of 1 lemon and add a squeeze of juice, then beat until just smooth – it's really important not to over-mix it.
Once cooled, use a thin, serrated knife to halve the sponges horizontally into rounds. Reserving the prettiest sponge for the top, spread 1 tablespoon of lemon curd onto one of the cooled sponges, then layer over one-third of the icing. Place it, icing-side up, onto a cake stand. Repeat with the remaining ingredients, then top with the final sponge.
To make the drizzle icing, sieve the icing sugar into a large bowl, then gradually whisk in 1 tablespoon lemon juice until it forms a good drizzling consistency, adding a squeeze more juice to loosen, if needed. Spread the icing onto the cake, dot over the lemon curd, then use a skewer to ripple it through. Scatter over a few edible flowers (if using), then serve. Enjoy!
You can make the cake mixture into cupcakes if you'd perfer – simply divide it between two 12-hole muffin tins and bake for 20 minutes, or until an inserted skewer comes out clean. Decorate with the drizzle icing and serve.