01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - Whisk together flour, baking powder, and salt in a medium bowl.
03 - Beat butter and sugar in a large bowl until light and fluffy, approximately 2-3 minutes.
04 - Mix in egg and vanilla extract until fully incorporated.
05 - Gradually blend dry ingredients into wet mixture until dough forms.
06 - Divide dough in half, flatten into disks, wrap in plastic, and refrigerate for 30 minutes.
07 - On floured surface, roll dough to 1/4-inch thickness. Cut with round or flower-shaped cutter.
08 - Place cookies 2 inches apart on prepared sheets. Bake 10-12 minutes until edges turn golden.
09 - Let rest on baking sheet for 5 minutes, then transfer to wire rack to cool fully.
10 - Beat butter until smooth. Gradually add sifted confectioners sugar, mixing thoroughly.
11 - Add milk, vanilla, and salt. Beat 2-3 minutes until fluffy. Adjust consistency with additional milk if needed.
12 - Divide buttercream into separate bowls and tint with food coloring gels as desired.
13 - Fit piping bags with small star, petal, and leaf tips. Fill with colored buttercream.
14 - Pipe flowers and leaves onto completely cooled cookies.
15 - Allow decorated cookies to rest at room temperature until buttercream firms slightly.