In a medium mixing bowl, whisk cake flour, cornstarch, baking powder, and kosher salt together. Set aside.
In a large mixing bowl, using a hand mixer, cream unsalted butter and granulated sugar together until combined.
Add in egg, vanilla extract, and almond extract.
Stir in sour cream and mix until well blended.
Add in dry ingredients and mix until just combined, using a rubber spatula to scrape down the sizes. Do not over mix.
Cover with plastic wrap and chill for a minimum of 60 minutes.
When ready to bake, preheat oven to 350℉. Line a baking sheet with parchment paper.
To portion the dough, scoop about 3 Tablespoons out, dust hands with powdered sugar, and roll into a ball. Place on a baking sheet, about 3 inches apart. Flatten with the bottom of a glass or flat measuring cup, dipped in powdered sugar. Cookies should be between ½” and ¼” thick.
Bake for 9-11 minutes; rotating the baking sheet halfway through. Cookies should be just lightly golden – NOT BROWN. Cookies will continue to bake on the cookie sheet while cooling. Cool completely before frosting.
For frosting, beat unsalted butter for 1-2 minutes, or until it has lightened in color and is creamy.
Add in the powdered sugar, vanilla extract, kosher salt, and heavy cream, a Tablespoon at a time, until the desired consistency is reached. Add food coloring to tint, if desired.
Frost cookies, leaving a small rim of the cookie exposed. Top with sprinkles or jimmies to decorate.
