If you are using frozen raspberries, half an hour before you will start making the cake, pour some warm water over them and leave them at the room temperature. The raspberries will melt and the water will get infused with the aroma. You will use this water later for the syrup. If you are using fresh raspberries, blend a few of them in 100 ml (1/2 cup) water and set it aside for the syrup.
Beat the eggs with melted butter and sweetener until you get a smooth emulsion. Add sea salt and keep beating.
Mix baking soda with citric acid and add it to the emulsion. Keep beating.
Add 1 tbsp psyllium and start adding coconut flour spoon by spoon: The mixture will thicken. Now add rum and beat one more minute. You can add orange peel essential oil (edible) in the end, but this is optional.
Line a 30x20 cm (11x9-inch) pan with parchment paper and pour in the batter. Bake at 180ºC ( 350ºF) for 20 minutes and leave it in the oven for another 5 minutes to gradually cool down. Cut the sponge cake in half to create 2 layers.
Boil 100 ml (1/2 cup) raspberry infused water with 1 tbsp sweetener, rum and 1 tsp butter.
Using a spoon sprinkle the syrup all over the sponge cake and let it cool down totally.
Place 500 g (17.6 oz) mascarpone into a deep bowl and add lemon zest. Add the sweetener. Drain the raspberries and add them too.
Using an electric mixer mix them at the highest speed so that all the raspberries unify with the mascarpone. The mousse will not be totally smooth as the one in Strawberry fields forever cake. if you want it to be smooth, then use the method from that recipe which you can follow in this link. Place the first layer on a wide plate and then place 1/3 of the filling on it. Place the other layer of cake on top and cover the whole cake with the rest of the filling/icing. Decorate with coconut crumbs and berries. Try to create a spiral design on top, just like the galaxy!
Serve after it's well chilled and try cutting 20 pieces of this amount of cake to match the macronutrient ratio at the bottom of this page.