Sift your pastry flour, almond flour, salt, and cinnamon into a mixing bowl and set aside.
Next, add your butter and powdered sugar to a separate mixing bowl and cream together until light and fluffy. This should take about 2-3 minutes in a standing mixer. Once creamed, add in your flax egg, vanilla, and sifted dry ingredients and mix until a thick dough is formed.
Remove the dough from the mixing bowl and use your hands to form into a large ball. Then, roll the dough between 2 pieces of parchment paper until about ¼" thick in height.
Next, use your Linzer cookie cutter to cut out an even amount of top and bottom cookies (with and without the heart-shaped insert). Each time you cut out cookies, form the scraps into a ball and roll out again until no dough is left.
Add the cookies to a lightly greased baking sheet or a baking sheet covered in parchment paper and place into the fridge for at least 10 minutes. This step is important so the cookies don't spread much while baking.
Preheat the oven to 350F while the cookies are in the fridge. Take the cookies out of the fridge and bake for 12 minutes. Remove from the oven and let cool on the baking tray for 2 minutes. Then, move to a cookie cooling rack to cool to room temperature.