1. Line a 20cm square loose-bottomed tin with parchment paper. Melt the Dr. Oetker Milk Chocolate and butter in a large heatproof bowl set over a pan of simmering water. Stir occasionally until melted, then add the Dr. Oetker Madagascan Vanilla Natural Extract and stir.
2. Add the Dr. Oetker Heart Marshmallows, popcorn and cranberries to the melted chocolate and mix well, ensuring all the pieces are coated. Spoon into the prepared tin, then press down to pack the mixture into the tin.
3. Break the Dr. Oetker White Chocolate into a small microwaveable bowl. Heat in the microwave for 30 sec bursts, stirring halfway, until the chocolate is melted. Using a teaspoon, drizzle the chocolate over the rocky road in the tin. Leave to cool, then cover and chill for at least 2 hrs until set. When ready to serve, stand at room temperature for around 15 mins, before removing from the tin and peeling away the lining paper. Use a large, sharp knife to cut into 12 squares.