Mix the butter, sugar, egg and vanilla: In a large mixing bowl or stand mixer, beat the softened butter and sugar together until combined. Add the egg and vanilla, then mix again.
Add the dry ingredients: Add the flour, ground almonds, baking powder and cinnamon.
Form the dough: Mix until the ingredients begin to come together, then use your hands to form a ball of dough.
Chill the dough: Flatten the dough into a disc, wrap it in cling film and refrigerate for 30 minutes.
Prepare the oven and trays: Preheat the oven to 200°C / 180°C fan / 400°F / Gas 6. Line two baking trays with baking parchment or silicone baking mats.
Roll out the dough: Roll the dough to approximately 3 mm (⅛ inch) thick on a work surface lightly dusted with icing sugar. Alternatively, roll it between two sheets of baking parchment.
Cut out the biscuits: Cut the dough into your chosen shapes. As the dough is quite soft, use a large knife or palette knife to lift the biscuits carefully onto the prepared baking trays.
Reroll the remaining dough: Gather the leftover dough, roll it out again and continue cutting biscuits until all the dough has been used.
Use the parchment method, if preferred: When rolling the dough between sheets of baking parchment, cut out the shapes while leaving approximately 1 cm between each biscuit. Remove the excess dough, then transfer the parchment and biscuits directly onto the baking tray.
Add the optional topping: Mix a little additional cinnamon and sugar together, then sprinkle it over the biscuits before baking.
Bake the biscuits: Place the tray on the middle shelf of the oven and bake for 10–12 minutes, until the biscuits are lightly golden.
Cool: Remove the biscuits from the oven and transfer them to a wire cooling rack.