Grease and line a 23cm round springform tin with baking paper and set aside.
Make the green jelly according to the packet instructions and set aside on the bench to cool - do not place it in the fridge as you don't want it to set just yet.
Place the butter into the Thermomix bowl and melt for 2 minutes, 80 degrees, Speed 2. Add the biscuits and press Turbo until crushed and combined (you may need to scrape down the sides of the bowl partway through).
Firmly press the mixture into the bottom of the prepared tin and then place it into the fridge.
Dissolve gelatine powder (see notes section).
Place the condensed milk and lemon juice into a clean Thermomix bowl. Add the dissolved gelatine mixture and mix for 15 seconds, Speed 4.
Pour the mixture over the prepared base and place into the fridge until set.
Gently pour the cooled green jelly over the top of the slice and place into the fridge until set.
Make the red jelly according to the packet instructions and set aside on the bench to cool - do not place it in the fridge as you don't want it to set just yet.
Dissolve gelatine powder in the cold water (see notes section). Place the condensed milk and lemon juice into a clean Thermomix bowl. Add the dissolved gelatine mixture and mix for 15 seconds, Speed 4.
Carefully pour the mixture over the set green jelly and place back into the fridge until set.
Gently pour the cooled red jelly over the top of the slice and place into the fridge until set.