Grind the shortbread and speculoos biscuits finely in the food processor.
Add the melted butter and blend a little more.
Lay the biscuits on the bottom of a frame covered in cling film.
Leave in the refrigerator to set.
Meanwhile heat the Debic Panna Cotta until it is completely liquid.
Add the lemon zest and the double-cream cheese.
Pour the panna cotta onto the biscuit base and leave in the refrigerator to set.