In a bowl, mix the crushed biscuits/crackers with the melted butter. You should be able to mold the mixture with your hands. Fill the bottom of each of the mini muffin cups of your tray, pressing down on the mixture as needed. Leave to set in the refrigerator for at least 2 hours.
Add all ingredients to a blender and blend until smooth. Spoon mixture into muffin cups on top of the crust, filling each one to the top. Leave to set in freezer for 4 hours.