Cut the panettone into four pieces horizontally. Set aside the curd with the zest of 1⁄2 a clementine.
To firm peaks, whisk the creams with the icing sugar, clementine juice, and half a clementine zest. Cut the remaining clementine's into 1cm circles after peeling them.
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. Swirl over the remaining cream and drizzle over the curd.
Scatter the flaked almonds and clementine zest on top of the remaining clementine slices.