You should cover the shape with foil and lay crackers at the bottom until there is no free space.
In a medium saucepan add butter, brown sugar, put on fire, and simmer for 3-4 minutes until the mass will be homogeneous and the sugar melts.
After that, pour sugar mixture on crackers, spread with a spoon evenly, put in the oven for 10minutes, ~ 375’ F, before bubble formation. Then take out this form from the oven. Put chocolate crisps on the top, spread it with a spatula, and wait until it melts completely.
When chocolate crisps meltaway, put chopped nuts on top, put sweets to freeze for a couple of hours.