Place the sugar and water in a pan and bring to the boil over high heat. Allow to cool, then stir in the lime juice. Set aside.
In a mixing bowl, whisk all ingredients to soft peaks.
Preheat the oven to 170°C and line a square 8 x 8 cm pan with baking paper.
In a bowl, cream together the butter and sugar. Crack in the eggs one at a time, beating after each addition, then stir in the lemon zest.
Fold in the flour and baking powder, then stir in the milk.
Pour the mixture into the pan and bake for 25 minutes. Allow to cool slightly, then transfer to a wire rack to cool completely. Once cooled, cut into pieces that will fit inside the verrine pots or glasses.
Place one piece of lemon cake at the bottom of the verrine pot.
With a Parisienne scoop, scoop the mango into balls. Gently toss the mango balls in the lime syrup, then place on top of the lemon cake.
Pipe the passionfruit cream on top of the mango balls.
Drizzle the melted milk chocolate on top of the passionfruit cream, then finish with the grated lime zest.