Hold out your non-dominant hand, palm up, (as if representing a
slice of bread on your palm. Form your dominant hand into a
"J"-handshape and brush the knuckle of the "J" on your palm twice as
if spreading jelly onto your piece of bread.
There are those who might consider the initialize sign JELLY to be Signed English. I disagree. I feel the sign is simply an initialized sign similar to "BLUE" or "GREEN." Just because a sign has an initial in it doesn't mean
it is Signed English.
However, it is not worth arguing about. If your local teacher has heartburn over initials (that happen to show up in signs very commonly used by Deaf people in real life) then just use the "spread on" sign.