Combine flour, baking powder, and salt in medium bowl and whisk until combined. Set aside.

Combine butter and sugar in bowl of electric mixer and beat until smooth. Beat in eggs and vanilla. Add flour mixture in three parts. Once dough comes together, cover bowl with plastic wrap and refrigerate for at least 1 hour.

Preheat oven to 400º F.

On a floured surace, roll out dough to 1/4 inch thickness. Using round cookie cutter or an overturned cup, cut dough into circles about 3 1/4 inches in diameter. Place cookies 1 inch apart on ungreased cookie sheet.

Bake 8 to 10 minutes, or until golden brown. Cool completely before icing.

Place egg whites in bowl of electric mixture; whisk until frothy. Add confectioners sugar a little at a time, until thick but still spreadable.

Place 1/3 of icing in a separate bowl. Add black food coloring to reserved icing and stir until color is uniform.

Decorate cooled cookies by covering with white icing and letting it dry (placing cookies in the refrigerator will speed this process up).

Place black icing in pastry bag or a plastic resealable bag and cut off a tiny bit of the corner to create a very small hole. Use black icing to draw eyes, nostrils, and stitched mouth on each cookie.