Bring the raspberries, sugar and water to the boil in a pan. Cover and simmer for approx. 10 mins., crush with a fork, then leave to cool.
In a bowl, beat the sugar, egg yolks and water using the whisk on a hand mixer for approx. 5 mins. until the mixture is light and fluffy. Beat the egg whites with the salt until stiff, add the sugar and vanilla, continue to beat until the egg whites turn glossy. Mix the flour and baking powder, add to the mixture in layers along with the egg whites, carefully fold in using a rubber spatula, transfer to the prepared tin.
Approx. 30 mins. in the centre of an oven preheated to 180°C. Remove from the oven, allow to cool slightly, remove the tin frame, tip the sponge out onto a cooling rack, remove the baking paper and leave to cool completely. Cut the sponge crosswise into thirds, allow half of the raspberry mixture to soak into the cut surfaces.
Whip the cream, icing sugar and vanilla paste until stiff. Mix one third of the whipped cream with the remainder of the raspberries, spread on top of two of the cut layers of cake, place the third cake layer on top. Spread the remainder of the whipped cream all around the cake. Sprinkle with hundreds & thousands, chill the cake for approx. 1 hr.
Divide the marzipan into thirds. Drizzle each third with a few drops of food dye and knead in the dye. Roll out each piece of marzipan between 2 sheets of baking paper to approx. 2 mm thick, cut into triangles. Decorate the sides of the cake with the marzipan triangles.