Peel the kiwi fruits and cut into small pieces.
Place the fruits into a small saucepan or pot.
Add the sugar and lemon juice and stir to mix.
Turn on the heat to a medium low and cook the fruits until they turn soft. Stir occasionally to prevent the fruits from burning.
Once the fruits have turned soft, turn off the heat. Let the mixture cool slightly before transferring into a food processor.
Blend or process the fruits to a puree. Pour into a dry container and keep it chilled until the mousse is ready to be assembled. The sauce needs to be completely chilled before assembling into the mousse (see Note 1).
Break the white chocolate into small pieces (see Note 2). Add into a heatproof bowl.
Pour 100ml of the cream into the chocolate and double boil until the chocolate melts. Stir to expedite the melting and to combine the cream and the chocolate to a smooth mixture.
Le the chocolate cool to room temperature.
In a separate large bowl, add the remaining heavy cream and whip to a soft peak stage (see Note 3).
Transfer 2 spoonful of the whipped cream into the chocolate mixture. Fold to combine. Repeat the process with another 2 spoons of whipped cream.
Finally, transfer the chocolate mixture into the remaining whipped cream and fold gently until well combined.
Reserve about 6 to 7 tablespoons of the white chocolate mousse into a piping bag fitted with a large star tip.
Also set aside about 4 to 5 tablespoons of kiwi coulis. Add the remaining coulis into the remaining chocolate mousse. Fold gently until well combined.
Transfer the kiwi chocolate mousse into a piping bag. Snip the tip and pipe the mousse into prepared mousse cups.
Tap the cups gently to level the mousse.
Next, divide the earlier reserved kiwi sauce onto the top of each filled mousse cups. Use the back of a small teaspoons to level the sauce on the mousse gently, making sure it does not get mixed with the mousse underneath.
Finally, pipe a large star with the earlier reserved white chocolate mousse (in the piping bag fitted with the star tip). Decorate with a small kiwi slice each if preferred.
Chill the mousse for at least 1 to 2 hours before serving. The mousse is best served completely chilled.