Take dark chocolates in a bowl. Melt them using a double boiler. Melt the white chocolate too separately, in the same way. Pour the melted dark chocolate into a plastic mould tray. Fill all parts of the cups with the chocolate. Place this tray in a refrigerator. Mix cream, mint toffee powder and mojito syrup in the melted white chocolate. Whisk it well using a whisker. Refrigerate this mixture too for ten minutes. Whisk the white chocolate mixture again after refrigeration. Mix it again with whipped cream and transfer this mixture into a piping bag. Remove the dark chocolate coated tray from the refrigerator and gently take out the chocolate cups. Fill the cups with white chocolate mousse and garnish with mint leaves.