In a medium bowl, whisk together the flour, salt, baking powder, baking soda, and cornstarch. Set that aside for now.
In a large bowl, cream the butter and sugar using an electric mixer until it’s light and fluffy—give it a good 5 minutes.
Mix in the egg, vanilla extract, and almond extract, then stir in the sour cream.
Add your dry ingredients to the wet and mix just until everything comes together. Don’t overmix.
Shape the dough into a disk, wrap it up in plastic wrap, and chill it in the fridge for at least an hour to firm up.
When you’re ready to bake, preheat the oven to 375°F.
Roll the dough out to about ¼ inch thick, then cut into circles using a 3-inch cookie cutter.
Place the cookies on a parchment-lined baking sheet and bake for 8–9 minutes. You don’t want them to get too golden—just barely baked is perfect for that soft texture.
Let the cookies cool completely before frosting.
To make the buttercream, beat the butter until fluffy, then mix in the powdered sugar and vanilla. Add the milk gradually until you get a smooth, spreadable consistency—you might need a splash more depending on your texture.
Divide the frosting into 3 bowls and color each with food coloring of your choice.
Frost each cookie with a piping bag or offset spatula, top with Halloween sprinkles, and you’re done!