Preheat oven to 325° and line two sheet trays with parchment paper

Mix butter and cornstarch together until combined.

Add the powdered sugar and then the flour. Stir until completely mixed.

Roll into 1 teaspoon balls and place on pan.

Bake for 9-11 min or until just lightly brown. Watch closely because they brown quickly towards the end.

Press them down slightly as soon as they come out of the oven. You want them to be flat, not puffy.

Let cool completely and spread one tablespoon of cookie butter on the bottom side of a cookie. Place another cookie bottom-side down on top of it to form a sandwich.

Repeat until all cookies are used.