- Preheat the oven to 80C.
- For the Candied Rose Petals, whisk the egg white until frothy and then, using a small pastry brush or paintbrush, very lightly paint over both sides of each petal with the egg whites: do these in 2 or 3 small batches of brushing and then sprinkling lightly over both sides with the sugar. Shake off the excess and then lay the petals on a baking tray lined with baking paper. Place into the oven and cook until dry and crunchy, about 30 minutes, then set aside to cool.
- Once the rose petals have been removed from the oven, increase the oven temperature to 160C.
- For the Cake, grease a 23cm spring form cake tin with butter and line the bottom and sides with baking paper.
- Use the flat side of a large knife to crush the cardamom pods and place the seeds in the small bowl of a food processor, the outer pod shells can be removed and discarded. Add 150g of the shelled pistachios and blitz until the nuts are finely ground, the black cardamom seeds won’t grind down. Transfer to a bowl and add the almond meal, semolina, baking powder and salt. Mix together until well combined and set aside.
- Place the butter and sugar into the bowl of a stand mixer fitted with a paddle attachment . Beat on medium-high speed until fully combined, taking care not to overwork or incorporate too much air into the mixture. With the machine still running, gradually add the eggs, scraping down the sides of the bowl a few times, making sure that each batch of egg is fully incorporated before adding the next. The mix will curdle once the eggs are added which is normal.
- Remove the bowl from the machine and add the dry ingredients to the mix, folding them in by hand and, again, taking care not to over mix. Next fold in the lemon zest, juice, rosewater and vanilla and then scrape the batter into the greased and lined tin. Level with a palette knife and then bake in the oven until a skewer inserted comes out clean but oily, about 55-60 minutes.
- Meanwhile, for the Cream, use a hand-held whisk to mix all the ingredients together until thickened, about 2 minutes. Place into the fridge until needed.
- 10 minutes before the cake comes out of the oven, make the Syrup: you want it to be warm when the cake is ready. Place all the ingredients for the syrup into a small saucepan over medium heat. Bring to the boil, stirring so that the sugar dissolves, and then remove from the heat: don’t worry that the consistency is thinner than you might expect: this is how it should be.
- As soon as the cake comes out of the oven, drizzle all of the syrup over the top of the cake. Sprinkle over the pistachios and then set the cake aside in its tin to come to room temperature. Remove from the tin and then pile the rose petals into the centre of the cake. Serve cake slices with a spoonful of the Cream alongside.
The cake keeps well, in an airtight container, for up to 5 days. The rose petals should be sprinkled on when serving.