Preheat oven to 160˚C/320F˚ and line & grease an 8" baking tin as required.
Sift the flour & baking powder together & set aside.
Place chocolate and cream in a roomy bowl and microwave on medium heat in 30 second bursts until the chocolate is almost melted, then stir until it's all melted.
Beat the butter & sugar until light and creamy.
Add egg, one at a time, beating well between additions. If you're worried about curdling, at a tbsp of flour with each egg.
Add the vanilla, rose water & chocolate mix & fold in gently, if using a tabletop mixer, at its lowest speed.
Add the flour, again, fold in gently.
Finally, add the raspberry coulis, again, fold in gently, don't worry about tiny streaks.
Pour into prepared tin & bake for about 45-60 minutes. I know that's a huge range, really does depend on your oven.
When done, leave it to cool completely before icing. Removing it from its tin will speed this up.
Halve the cake and fill with raspberry jam.
White Chocolate Buttercream
Melt the chocolate in a bowl in the microwave in 30 second spurts, stirring each time. Leave to cool for a few minutes.
While waiting for the chocolate to cool, beat the butter and sugar as above.
Add the melted chocolate.
Add raspberry coulis and stir gently to mix. Don't worry about streaks.
Pure White Chocolate Covering
Melt chocolate on medium power in a microwave at 30 second burst until melted.