Melt the plain chocolate slowly in a bowl over a saucepan of simmering water. The trick is to not poke, prod or stir it. Just wait patiently until about a third of it is melted, then push the solid bits down into the liquid and lower the heat.
Whilst it is melting, spread the almonds over a baking sheet and sprinkle with icing sugar (if there isn't much room you may need to do this in 2 batches). Toast them under the grill on the lowest heat setting until the nuts are golden and the sugar is melted and glistening. Set aside to cool.
Also while the chocolate is melting, spread the pistachios over a chopping board and crush by rolling a rolling pin over them.
Line a baking tray with foil or greaseproof paper and spoon a small dessertspoon of chocolate on top. Spread it into a roughly round shape with the back of the spoon and repeat until all the chocolate is used up. The thickness of the snaps comes down to personal preference, I prefer them thinner but then you have less time to add the toppings before they set.
Top the chocolate puddles with half of the pistachios, half of the toasted almonds and a small pinch of salt on each.
Place them in the fridge for at least 20 minutes to harden and cool. Meanwhile crack on with the white chocolate version, this time replace the salt with a small sprinkling of the spices mixed together.