Preheat oven to 180C. Turn on ice cream machine to chill.
For the Lemon Aspen Ice Cream, place sugar and egg yolks into the bowl of a stand mixer fitted with a whisk attachment and whisk until pale.
Meanwhile, place cream and milk in a small saucepan over medium heat and bring to the boil. Remove from the heat and, whilst whisking continuously, slowly add hot cream mixture to the yolk and sugar mixture.
Return the mixture to the saucepan and place over a medium heat. Heat mixture to 80C, stirring continuously. Remove from the heat and strain anglaise mixture through a fine sieve into a clean bowl then set over an ice bath and whisk until completely cold.
Slowly incorporate lemon aspen juice into the cooled anglaise, one quarter of a teaspoon at a time.
Transfer the mixture to the pre-chilled ice cream machine and churn until set then transfer to the freezer until needed.
For the Wattleseed Biscuit, place butter and sugar into the bowl of a stand mixer fitted with a paddle attachment. Cream butter and sugar until pale and fluffy. Fold in the flour and wattleseed and continue to mix until a soft dough has formed.
Place a sheet of baking paper onto a clean work surface. Transfer the dough to the baking paper and top with a second sheet of baking paper. Roll out the dough between the two sheets of baking paper to 3mm thickness.
Remove the top layer of baking paper and place the dough on baking paper onto a large baking tray. Bake in the oven until golden, about 10-12 minutes. Remove from the oven and while still warm, use a 10cm cutter to cut out 4 biscuit rounds. Cut each round into half and set aside on a wire rack to cool.
For the Quandong Jam, place all ingredients into a small saucepan over medium heat and bring to the boil. Reduce heat and simmer until syrupy, about 5-6 minutes. Remove from the heat and set aside.
For the Fresh Cheese Mousse, place all ingredients into the bowl of a stand mixer fitted with a whisk attachment and whisk on medium speed until the mixture reaches firm peaks. Transfer to a piping bag and set aside in the fridge.
To serve, spoon one tablespoon of Quandong Jam in the centre of the serving bowl. Sprinkle with some fresh diced quandong. Top with a quenelle of the Lemon Aspen Ice Cream. Pipe Fresh Cheese Mousse around the base of the ice cream and lean two Wattleseed Biscuit halves onto each ice cream quenelle.