Set the oven to 180°C / 360°F with the fan.
In a food processor with a steel blade, place the pistachios and begin to crush them into small pieces but not like a powder.
Add the flour, butter and sugar and continue processing until you get a crumbly mixture.
Transfer the crumbs to a baking pan and bake for 10 minutes.
Set the crumbs aside to cool.
In a bowl, place the white chocolate and whipping cream.
In 30 second rounds in the microwave, melt the chocolate with the cream. You can also do it on top of a pot with boiling water - it just may take longer.
The chocolate needs to melt completely and the batter needs to be smooth and unified.
Cool the chocolate and cream batter in the fridge for 1 hour.
In a stand mixer with the whipping attachment, whip the cooled chocolate cream batter to stiff peaks.
Place the mousse in a piping bag.
Prepare the cups you want to use to serve the dessert with.
Start building the layers - start with the pistachio crumble, pipe a layer of the white chocolate mousse and then add pomegranate seeds. Continue adding layers to fill the cups.
Keep the cups in the fridge until you serve the dessert.
Dig in!