Coat a tight springform pan with oil and make a base of dr Gerard sponge cookies.
Prepare the first layer from jelly (1 packet) and fromage frais (1 packet): dissolve jelly in 1/4 of the water amount given on the packet instructions, set aside to cool down a little and mix with fromage frais. Pour the mixture on the base made of dr Gerard sponge cookies and leave to set.
Prepare the second layer only from jelly (1 packet) of the same flavour that was used to prepare the layer with fromage frais: dissolve jelly in 1/2 of the water amount given on the packet instructions and set aside to cool down.
Having made sure that the mixture in the springform pan is set, pour it over with a layer of prepared jelly and again leave to set.
Repeat the process with each colour of jelly, sandwiching them, so that they create a rainbow cheesecake.