Place the butter in a bowl, whisk in the sugar and salt. Add the eggs one at a time and continue to whisk until the mixture becomes lighter in colour. Stir in the orange zest, juice and orange liqueur. Mix the flour, almonds and baking powder, stir into the mixture. Transfer the cake mixture to the prepared tin.
Approx. 1 hr. in the lower half of an oven preheated to 180°C. Remove from the oven, allow to cool slightly, remove the cake from the tin and leave to cool on a rack.
Combine the icing sugar with the orange liqueur and water, spread on top of the cake, sprinkle with flaked almonds.