Weigh out ingredients
You'll need all-purpose flour, baking powder, salt, butter, sugar, eggs, and vanilla extract.
Make the dough
Whisk together the flour, baking powder, and salt. In a separate bowl, beat the butter and sugar for 1-2 minutes. Beat in the egg and vanilla. Add in the dry ingredients. Mix until just combined.
Chill & Shape
Shape the dough into a flat disk and refrigerate for at least one hour or overnight. On a lightly floured surface, roll out the cookie dough to about ¼" thick and cut out as many snowflakes as you can with a cookie cutter.
Bake the cookies for about 10 minutes at 350 degrees F until barely golden around the edges. Allow to cool completely before decorating with royal icing.