Work the butter or margarine, Siúcra/McKinney's Granulated Sugar, flour and egg together. Divide the dough into two pieces, and colour one yellow and the other green. Place in plastic bags and leave to rest in the fridge for 1 hour.
Roll out both doughs on a floured surface and cut out small round shapes with cookie cutters. Overlap yellow and green circles so that they form small wreaths.
Place on baking sheets lined with baking parchment and bake at the centre of the oven at 175°C for about 10 minutes. Leave to cool on a wire rack. Store in a dry, airtight container.
You can also roll the dough into lengths that you plait together and then shape into wreaths.