In a large bowl, sift together the cake flour, all-purpose flour, cornstarch, baking powder, and salt.
In the bowl of a stand mixer fitted with the paddle attachment, cream together the butter and sugar for 3 to 4 minutes, until the mixture is light yellow and creamy.
Add the eggs to the mixer, beating in one at a time. Then add the almond extract and mix for 30 seconds.
Gradually add the dry ingredients mixture to the wet mixture in the mixer until just ingredients are fully combined.
Shape the dough into a disc, wrap in plastic wrap or wax paper, and chill in the refrigerator for 30 minutes.
Preheat oven to 350° degrees.
Using a medium cookie scoop, portion out dough and roll the dough into balls.
Place the sanding sugar (or sugar in the raw or colored sugar) in a shallow bowl. Roll the balls in the sugar until completely covered. Place on cookie sheets about an inch or two apart. Using the palm of your hand or the bottom of a glass, press down on the top of each cookie to flatten them down a bit (cookies will not spread much while baking).
Bake at 350°F for 7-9 minutes. Allow the cookies to cool on the pan for about 2 minutes, then transfer to a cooling rack to cool completely.
Notes
Flours: the blend of cake flour and all-purpose flour are what give these cookies their super soft yet stable texture. If you only have all-purpose flour, you can use all all-purpose flour in a pinch, but the cookies will likely come out firmer and denser. Do not use bread flour or whole wheat flour with this cookie recipe. I have not tested this recipe with gluten-free flours so if you try it, please leave a comment and let us know what flour you used and how they turned out!Storage: Store cookies in an airtight container at room temperature for up to one week. Freeze: You can store cookies in a freezer-safe, airtight container in the freezer for up to two months.