Whisk the flour, baking powder, baking soda, and salt together in a mixing bowl. Set aside.
Place the butter and granulated sugar in a second mixing bowl. Sift the powdered sugar through a fine mesh sieve into the bowl. Mix the butters and sugars on medium to high speed until light and fluffy, about 1 to 2 minutes (if using a stand mixer, use the whisk attachment).
Add the eggs, corn syrup, and almond extract to the butter. Mix until well combined and fluffy, stopping the scrape down the sides of the bowl halfway through mixing.
Sift the flour mixture into the bowl of butter. Dump in any salt granules that don’t go through the sieve into the bowl. Mix on low (switch to the paddle attachment if using a stand mixer) until the flour is almostcombined. Finish mixing the dough by hand with a rubber spatula or wooden spoon, being sure to incorporate any dry bits of flour at the bottom of the bowl.
Quickly and gently gather the dough together using your hands. Place the dough on a work surface and divide it in two. Use your hands to shape each portion of dough into a disc. Wrap each dish gently but tightly in plastic wrap. Chill the dough discs in the fridge for a minimum of one hour.
Bake The Snowflake Sugar Cookies
Remove a disc of dough from the fridge. Lightly flour a piece of waxed paper on a work surface. Place the dough on top of the paper, sprinkle it lightly with flour, and place a second piece of wax paper on top. Starting in the middle of the dough, gently use a rolling pin to start rolling just to the edge of the dough. Turn the dough a quarter turn and repeat until the dough is smoothly rolled out to your desired thickness (I like these cookies fairly thick, somewhere between ¼ and ½ inch (½ to 1 ¼ cm).
Cut shapes with snowflake cookie cutters. Some of the cookies will stick inside the cookie cutter. Use the tip of a finger to gently press and push the cutouts onto a plate or small tray lined with parchment.
Repeat the process, re-rolling the scraps when needed, until all of the dough is gone. Place the unbaked cookies in the freezer for 20 minutes (or longer—see the tips & notes section).
While the unbaked cookies are in the freezer, preheat the oven to 350ºF (180ºC) and line two baking sheets with parchment paper.
Remove the cookie cutouts from the freezer. Arrange them on the prepared baking sheets leaving some room in between them. Place the baking sheets in the oven and bake the snowflake cookies for 10-12 minutes, or until the cookies are pale gold on the edges.
Remove the cookies from the oven and place the baking sheets on wire cooling racks. After 10 minutes, use a small offset spatula to transfer the cookies from the sheets directly to the racks to cool completely before decorating.