Break the dark chocolate into a heatproof bowl and place over a saucepan of barely simmering water to melt.
Meanwhile, line a baking tray with baking parchment. Once the chocolate has melted, scrape it out of the bowl on to the centre of the paper using a spatula. Carefully spread the chocolate to form a rectangle approx. 18 x 23cm (7 x 9 inches). Tap the tray lightly on the work surface to smooth the chocolate and leave in a cool place to set.
Melt the white chocolate in the same way. Remove the bowl from the water and mix in the gel food colour to make a pale green shade.
Once the dark chocolate layer has set, pour the green chocolate out of the bowl on to the dark chocolate. Using a spatula carefully spread the green chocolate to almost cover the dark chocolate. Tap the tray lightly on the work surface to smooth the chocolate.
Working quickly, before the green chocolate sets, decorate the top with Dr. Oetker Wafer Daisies, Sugar Butterflies and Sugar Strands, then leave in a cool place to set.
Once the chocolate is firm, break into pieces and either serve as they are, or pack pieces into boxes or cellophane bags for gifting.