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 with electric mixer until light and fluffy, about 3 minutes.
04 - Beat in egg and vanilla extract until fully combined.
05 - Gradually mix in dry ingredients just until dough forms.
06 - Divide dough into two discs, wrap in plastic, and refrigerate for at least 30 minutes.
07 - On lightly floured surface, roll dough to 1/4-inch thickness. Cut with bunny-shaped cookie cutter and place 2 inches apart on baking sheets.
08 - Bake for 8 to 10 minutes until edges begin turning golden. Cool completely on wire rack.
09 - Beat softened butter until creamy. Gradually add powdered sugar, milk, and vanilla, beating until smooth. Tint with food coloring if desired.
10 - Frost cooled cookies with buttercream using piping bags or spatulas. Add candy eyes or sprinkles for bunny faces. Let frosting set before serving.