Whisk the flour, baking powder, and salt in a medium bowl. Set the bowl aside.
Beat the butter and granulated sugar in a large bowl until light and fluffy. Add the vanilla bean seeds and egg. Mix until combined.
Stir the dry ingredients into the wet mixture until a dough forms. Shape the dough into a disk, wrap it, and chill for 30 minutes.
Heat the oven to 350 degrees. Roll the dough to 1/4-inch thickness on a lightly floured surface. Cut into rectangles and place them on a lined baking sheet.
Bake for 10 to 12 minutes until the edges turn lightly golden. Cool the cookies completely on a wire rack.
Mix the powdered sugar and milk in a bowl to make icing. Divide the icing into two bowls. Tint one bowl green and the other black.
Spread green icing on each cookie for the face. Pipe black icing for hair and stitches. Press two candy eyes onto each cookie while the icing is wet.