Whisk together dry ingredients (except sugar) until well combined, set aside.
In a stand mixer, cream together butter and sugar until smooth and fluffy. Add in egg, beat well. Add vanilla extract, and mix until well incorporated and smooth.
Slowly add dry mix to the mixer bowl, and carefully mix until well incorporated and smooth.
Wrap dough in plastic film, chill for 1 hour.
Preheat oven to 350 F (180 C), line baking sheets with parchment paper.
Generously sprinkle clean work surface with corn starch, roll dough to 1/8″ thick.
Use cookie cutters to cut out rounds, place cookies 1″ apart on greased baking sheets. For added accuracy, use a fork to gently make a grid pattern on top of half of the cookie rounds, before using drinking straw to punch a small hole in the center of each of those marked rounds.
Bake cookies for 8-10 minutes, or until bottoms look lightly golden.
Allow cookies to cool on baking sheets for at least 5 minutes before moving. Cookies need to cool completely before filling, so make your filling now!