Chocolate ghost-face ice cream cookie sandwiches

Pair flat cookies of similar size and shape and turn half of them flat side up.

Roughly chop white bar chocolate (stab and wiggle to start), transfer to a bowl and microwave about 10 seconds at a time until 75 to 80% is melted, then stir until smooth. Test white chocolate chips first: they often do not melt.

For the dark chocolate without a microwave: about an inch of water in a saucepan on the lowest heat, a bowl over the top, dark chocolate chips in; leave until about 75% melted, then stir until smooth. Stirring unmelted chocolate in gives a nicer, crispier texture when set.

Spread a heaping spoon of dark chocolate on the flat side of a cookie almost to the edge; tap and shake to level it.

While the dark chocolate is still wet, pipe a pool of warm white chocolate from a snipped plastic bag and shape the ghost's bottom with the end of a spoon; tap to flatten.

Pipe the eyes and screaming mouth with dark chocolate from a second snipped bag, using only a little and pulling straight up; add small white baby ghosts with tails.

If the chocolate sets before you finish, warm the cookies for a few seconds in a barely warm oven to re-melt it slightly.

Let sit at least an hour until completely cool and dry; they should keep a little shine.

Scoop ice cream on the bottom cookies, place the decorated tops over and press down gently through parchment paper with something heavy and flat, not so hard that the ice cream squeezes out.

Freeze until frozen solid before serving.