In a large bowl, sift together flour, baking powder and salt. Whisk to blend and set aside. In an electric mixer fitted with the paddle attachment, cream butter and sugar until fluffy and pale, about 5 minutes. Beat in vanilla extract. Beat in egg.
Add flour mixture and mix on low speed until thoroughly combined. Divide dough into two equal parts. Flatten each portion into a disk and wrap well in plastic wrap. Chill in the refrigerator for about 45 minutes.
Preheat your oven to 170ºC (conventional). Remove both disks and unwrap. On a lightly floured work surface, roll both disks out to about 5cm thick. Cut out 12 circles using a 7cm round cutter & 24 circles using a 3cm round cutter for the bunny feet. Place cut-outs on prepared baking trays, spacing them 3cm apart.
Bake for 12-14 minutes for the large cookies and 8-10 minutes for small cookies, or until edges are golden brown. Transfer baking trays to a wire rack to cool.
To make the pink icing, stir together icing sugar, milk & a few drops of red food colouring, until smooth & thick. Spread pink icing over large cooled cookies and press a marshmallow into the centre to make a tail. To make the white icing stir together the icing sugar & milk until smooth & thick and spread over small cookies.
To assemble position two small cookies over the icing on the large cookie to resemble feet. Once icing is set, spread a small circle of pink icing in the middle of the feet and press three pink sugar pearls into the icing to resemble toes.