Line a baking sheet with parchment paper.

In a large bowl, beat the softened butter and sugar until the mixture looks light and fluffy.

Add the egg and vanilla extract.

Mix again until smooth.

Add the flour, baking powder, and salt.

Mix just until a dough forms.

Divide the dough into two equal pieces.

Put one half in a separate bowl and tint it blue.

Color the second half green.

Chill the dough for 20 to 30 minutes.

Roll out the blue dough on a lightly floured surface to about 1/4 inch thick.

Cut out round circles with a cookie cutter.

Place the blue circles on the prepared baking sheet.

Roll out the green dough to the same thickness.

Cut or pinch off small uneven pieces to place on top of each blue circle.

Press the green dough pieces gently onto the blue dough so they stick without smashing the shape flat.

Bake for 8 to 10 minutes.

Watch for the edges to look set and just barely golden.

Let the cookies sit on the pan for 5 minutes after baking.

Move them to a wire rack to cool completely.