Preheat the oven to 350°F (175°C).
In a large bowl, cream together the butter and sugar until light and fluffy.
Beat in the egg and vanilla.
Gradually add flour, baking powder, and salt to the butter mixture, mixing until a smooth dough forms.
Divide the dough into two parts. Add blue food coloring to one part and green to the other, and mix until the colors are even.
Roll out both doughs separately to about 1/4 inch thickness.
Use a round cookie cutter to cut out circles from both doughs.
Place a blue circle on the parchment paper, then add small pieces of green dough to represent the land.
Bake for 8–10 minutes or until the edges are lightly golden.
Allow the cookies to cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.