Cut the panettone into four pieces horizontally. Combine the curd and half a clementine's zest in a mixing bowl.; set aside.
Pare the zest from two clementines. Whisk the creams with the icing sugar, clementine juice and the zest of half a clementine to stiff peaks. Peel the remaining clementines and cut into 1cm rounds.
Drizzle a quarter of the curd over a quarter of the cream on the bottom panettone slice. Repeat until you reach the top slice, then top with a few slices of clementine. Drizzle the remaining cream over the curd in a swirling motion.
Scatter the flaked almonds and clementine zest on top of the remaining clementine slices.