Preheat the oven to 190ºC/gas mark 5. Line a 12-hole cupcake tin with 12 cupcake paper cases.
Beat the spread and sugar until very soft and fluffy. Beat in the eggs, then add the flour, baking powder and cocoa powder.
Stir in the chocolate chips. Spoon the cake mixture between the 12 cupcake cases. Bake for 20-25 minutes, then removed from the oven and cool on a wire rack.
Meanwhile, whisk the butter and icing sugar together until very soft and fluffy. Add 2 drops rose water, 3 drops food colouring and the milk and whisk again for a few minutes until very creamy.
Fit a rose petal nozzle into a large piping bag. Fill the piping bag with the buttercream. Holding the nozzle directly over the centre of the cake, pipe the icing to create a rose shape.