For the biscuit, cream the butter and sugar with an electric mixer until pale and light. Add vanilla essence and mix well. Add the egg and mix thoroughly.
Sift together the flour, baking powder, Bi-Carb and salt. Gradually add to the creamed mixture to form a dough. Wrap dough in cling film and refrigerate for an hour.
Preheat oven to 170C. Line three oven trays with baking paper.
Lightly flour the work surface and roll out the dough evenly to a thickness of approximately 5mm. Using cookie cutters, cut out circle shape and then create a ring using a smaller cookie cutter round on the inside. Arrange on the prepared baking tray.
Bake for 10-12 minutes on the middle shelf.
Allow the biscuits to cool completely before decorating.
To make icing, using an electric mixer, beat butter until light and fluffy. Add icing sugar 1 cup at a time, beating well in between. Add milk and vanilla essence and mix until full combined.
To decorate, use a piping bag fitted with a star tip to pipe around the cookie. Whilst the buttercream is still fresh, add the eyes.
Remaining little rounds can be baked for 7 to 10 minutes for a little biscuit snack!