In a large bowl, or the bowl of your stand mixer, cream together the softened butter and sugar until smooth and fluffy
Add the egg and the vanilla and mix until incorporated
Next, add the ground almonds and lemon zest and mix until combined
Sift in the flour, baking powder, cinnamon and salt and mix until a smooth dough forms. Divide the dough into two balls for ease of rolling, then cover with plastic wrap and place in the fridge for 30 minutes to 1 hour
Preheat the oven to 180°C and line two large baking sheets with baking paper or silicone baking mats
Flour your surface well, then remove one of your dough balls from the fridge and roll with a rolling pin to around ½ cm in thickness. You want these to be quite thin as they will be sandwiched together
Using your preferred shape cookie cutter, cut out your shapes and place on your prepared baking sheet, leaving space between the cookies
Use a smaller cutter to cut the centres out of half of the cookies
Bake for around 7 – 9 minutes. You do not want them to brown
Remove and let cool for around 5 minutes on the baking sheet, then place the cookies on a wire cooling rack to cool completely before filling and decorating
Repeat with the remaining dough. Remember to have equal amounts of tops and bottoms for your cookies
When the cookies are all completely cooled, spoon around ¼ – ½ a teaspoon of jam onto the bottoms, spreading slightly. Do not go right to the edges as it will ooze out when placing to tops on
Next, place all the tops together and give a very generous sifting of icing/powdered sugar (this is done before putting the tops on the bottoms so that the jam is visible)
Finally, gently place the tops on the jam filled bottoms and push down slightly to sandwich together