Whisk together all dry ingredients (except sugar and corn starch) until well combined, set aside.
In a stand mixer, cream together butter and sugar until smooth and fluffy.
Add in eggs, one at a time, beating well between each addition. 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 400 F (200 C), line cookie sheets with parchment paper
Generously sprinkle clean work surface with corn starch, roll dough to ¼" thick (can be slightly
thicker).
Use cookie cutters to cut out whatever shapes you’d like.
Place cookies 2" apart on prepared cookie sheets, bake for 8-10 minutes, or until bottoms look lightly golden.
Allow cookies to cool on cookie sheets for at least 5 minutes before moving.
Cookies need to cool completely before decorating.
Decorate with Royal Icing