First, combine dry ingredients. In a mixing bowl add flour, salt, baking powder, baking soda, and cornstarch. Whisk together and set aside.
Then, in another bowl, beat sugar and butter together until they are fluffy. Add the egg, vanilla, and almond extract, and beat for two minutes. Pour in the sour cream and mix until everything is well combined.
Mix the dry ingredients with the wet ingredients. Then, use a hand mixer on the lowest speed until the ingredients are just blended. Use a spatula to scrape down the bowl.
Place dough on a lightly floured surface and gently knead into a smooth, firm ball. Wrap the dough in plastic and put it in the fridge for an hour.