Preheat oven to 180°C/Gas Mark 4. Grease two baking trays.
For the chocolate dough, cream together the butter and sugar in a large bowl. Sift in the flour and cocoa and mix to form a dough. Wrap in clingfilm and chill in the fridge for an hour.
Meanwhile, make the almond cookie dough by adding the butter and sugar to a large bowl and creaming together. Sift in the flour, add the ground almonds and almond extract and mix to form a dough. Wrap in clingfilm and chill in the fridge for an hour.
On a lightly floured surface, roll the chocolate dough to about 5mm (1⁄4in) thick. Stamp out one cookie in each size using the Lakeland 3D Christmas Cookie Cutter Set, dipping the cutters in flour first to prevent sticking. Place the cookies on a baking tray.
Repeat for the almond cookies. Place onto a baking tray and sprinkle with flaked almonds, gently pressing them into the dough.
Bake for 10-12 minutes. Cool on the trays for 20 minutes, then transfer to a wire rack to cool completely.
To assemble the tree, place the largest chocolate cookie onto a serving plate, followed by the largest almond cookie. Keep stacking and alternating the cookies to create a tapered Christmas tree shape.
For the finishing touch, spoon some Nutella, melted chocolate or icing on top of the smallest chocolate cookie to prop up the smallest almond cookie star. Dust with edible silk, if desired.