White or black patches on the florets or the stem are likely mold—you shouldn't eat it. The broccoli may also smell rancid, ...

Leave to cool. 3. When cool and beginning to set, mix in the broccoli, walnuts, salt, pepper and corn. 4. Transfer into the mould and leave to chill and set in the refrigerator. 5. When ready to serve ...

and since most of us don't have the patience to wait for broccoli to completely air dry, by putting it in the fridge still damp you're creating conditions in which mold can grow. Instead ...