Preheat your oven to 180°C or gas mark 4. Grease a 23cm spring form cake tin with butter and line the base with baking paper. Melt the chocolate in a heatproof bowl set over a pan of lightly simmering water. Make sure that the base of the bowl is not touching the water. Remove the bowl and leave to cool for a bit. In a mixing bowl, cream the margarine and sugar with an electric beater until light and fluffy. Add the eggs, one at a time, beating well after each addition. In a small bowl, sift the flour, cocoa powder, baking powder and salt. Fold these dry ingredients into the creamed batter.  Stir in the red wine, orange zest and the melted chocolate. Scrape the batter into the cake tin and bake for 40 minutes. Allow the cake to cool completely.

For the frosting, add the butter and Baileys to a bowl of a food mixer. Mix until the butter and milk are completely mixed. Add the powdered sugar and spices and beat on low until well incorporated. Move mixer up to medium-high speed, scraping sides and bottom of bowl often. If it is dry, add more milk and adjust accordingly. Frost the cooled cake with this mixture. Arrange the cranberries on top and scatter the dried rose petals.