Place the cherry halves into a bowl and pour over half of the almond liqueur. Set aside to macerate for 15-20 minutes.
Meanwhile, preheat the grill to medium. Sprinkle the oats onto a baking tray and toast under the grill for 4-5 minutes, shaking the tray occasionally as the oats cook to ensure they turn golden-brown all over. (Alternatively, preheat the oven to 160C/325F/Gas 3 and toast the oats for 12-15 minutes.)
Repeat the toasting process with the flaked almonds (these should take less time to turn golden-brown so keep an eye on them). Set aside to cool.
Bring a little water to the boil in a pan. Reduce the heat until the water is simmering, then suspend a heatproof bowl over the water, making sure that the bottom of the bowl does not touch the water.
Add the chocolate to the bowl and stir until just melted. Remove from the heat and set aside to cool slightly.
Drizzle the honey over the toasted oats. Add the honey-coated oats to the melted chocolate and stir well.
Add the remaining almond liqueur and one-third of the double cream to the chocolate mixture and stir until well combined.
Whip the remaining cream in a bowl with the icing sugar until soft peaks form when the whisk is removed.
Divide the chocolate-and-oat mixture among four tumblers or individual trifle dishes.
Next, spoon some of the whipped cream into each dish. Layer in the macerated cherries (saving four to use as a garnish).
Spoon in the remaining whipped cream, then sprinkle over the toasted almonds.
Chill the Black Forest cranachans in the fridge for at least 30 minutes, or until needed, to firm up.
Just before serving, garnish each dessert with one of the remaining cherries.