Preheat your fan oven to 175˚C or 350˚F. Line your baking sheet with baking paper.
In a medium sized bowl, sift together flour, baking powder and cardamom. Add ground pistachios and thoroughly combine using a whisk.
In another bowl, using an electric hand or a stand mixer, mix together butter and sugar until pale and fluffy (approx. 2-3 min)
Add an egg and vanilla extract and mix until everything is combined.
Add your dry ingredients to butter, sugar and egg mixture in TWO batches, mixing just until everything is incorporated and there are no lumps of flour. You don't want to overmix it, otherwise your cookies will get tough.
Divide it in two, wrap up in cling film forming a disc and put it in fridge for an hour or up to a week.
Once you're ready to bake the cookies, leave the dough at room temperature for 15 to 20 minutes, until it's ready to roll.
On a floured surface roll out the dough to a ¼ inch thick rectangle and cut out Christmas trees using a cookie cutter. Mine was approx. 2 inch (5 cm) long. Using a skewer, poke out the holes in half of the cookies, so they look like Christmas ornaments.
Bake the cookies for about 10-12 minutes. They should be lightly soft in the middle and golden. Transfer them to a cooling rack to cool completely.
quick cranberry jam
In a medium sized non-stick saucepan place together frozen cranberries and sugar. Cook it on a medium-high heat until it starts to boil, stirring occasionally. Reduce the heat and let it cook for 15-20 minutes until it thickens. Once it's done, strain the jam through a sieve or blitz it with an immersion blender, add orange juice and put it a clean glass jar. Let it cool in the fridge before using.
Assembly:
Dust half of your cookies (the ones with holes) with powdered sugar. Put a teaspoon of jam in the middle of each cookie but be careful not to spread it all the way to the end, so it doesn't ooze out when you sandwich the cookies. Place the other cookie on top and enjoy! Keep them in an airtight container to prolong their freshness.
Notes
Not all ovens are the same. I suggest baking a couple of "test cookies" to find out the best baking time or temperature. Get to know your oven!
If you still don't own one, I advise you to buy a kitchen scale - they're cheap and easy to use, and always guarantee the same results in baking!
If you're not using salted pistachios, then add ½ teaspoon of salt to your cookie dough!