In a medium bowl combine the flour, salt, starch and cardamom. Whisk to combine well. Set aside.

In a bowl of a stand mixer on medium, cream the butter until soft and fluffy, about 2 minutes. Stop the mixer and add the powdered sugar and mix on low until combined. Add in the vanilla extract and vanilla bean seeds or paste. Slowly add in the flour mixture and mix until combined.

Form the dough into two sections and form each section into a ball with your hands. Flatten into a disc and wrap with plastic wrap. Chill for one hour.

Preheat oven to 300 deg F. Prepare baking sheets with either parchment or silicone bake mats.

On a lightly floured surface roll out on dough disc at a time to ¼” thick. Cut out with 2” diameter snowflake shaped cookie cutters and place on cookie sheets about 2” apart. Bake for 10-11 minutes. Do not over bake or let them brown.

Let cool for a few minutes on the cookie sheets and carefully remove to a wire cooling rack to cool completely before filling and assembly. Since they are thin cookies they cool pretty quickly.

Make the buttercream while the cookies are cooling. You could also make this a day ahead of time and bring to room temperature before using, just whip again in your mixer to make it light and fluffy.

Set a pan of water over the stove and bring to a simmer. Set your mixing bowl over the pan to make sure it doesn’t touch the water, either pour out some of the water or add a foil ball to keep it from touching. In the stand mixer bowl, combine the egg whites, sugar and salt.

Set the bowl over the pan of simmering water until it reaches 160 deg f. ( use a candy thermometer). Return the bowl to the stand mixer and attach the whisk attachment. Slowly bring the speed all the way up and whip the mixture until thick and glossy and the bottom of the mixer bowl is cooler to the touch, about 7 minutes. Lower the speed to medium and add in the butter one tablespoon at a time allowing a few rotations of the whisk in-between each addition.

Stop to scrape down the sides of the bowl and bring the speed up to high and whip until the buttercream comes together. Mix the espresso powder with water then add to the buttercream. Whip to fully incorporate for another minute.

If piping the buttercream for the filling - fit a piping bag with a small open star tip and fill with some of the buttercream, squeeze to get rid of any air. I always squeeze a little back into the mixing bowl when getting rid of the air.

Take one cookie and spread or pipe some of the buttercream on the underside of the cookie (the side that touched the baking sheet when baking) and top with the other cookie. Repeat with remaining cookies. Chill until ready to serve. Serve chilled or at room temperature.