Gryffindor: knead the red fondant until pliable. Rub your hands with a little shortening from time to time to prevent the fondant from sticking.
Grease the working surface and the rolling pin with a small amount of shortening. Roll to a long strip, about 40 cm/ 15 ½ inches long and about 6 cm/ 2.5 inches wide.
Cut three strips with the help of a ruler and a sharp knife, they should be about 32 cm/ 13 inches long and 1,5 cm/ 0.6 inch wide. Trim the ends.
Take one cupcake and place it upside down in front of you. Grease the part of the scarf which will be attached to the cupcake with very little water or shortening to help it stick to the muffin paper.
Carefully wrap one of the red stripes around the base of the cupcake and gently twist around to make it look as if tied. Turn the cupcake around and gently press all around the scarf and on the knot to stabilize it. Shorten the ends if too long.
Place the cupcake onto the serving platter and arrange the ends of the scarf neatly on the platter. Cut the fringes of the scarf using a small sharp knife.
Slytherin, Hufflepuff, Ravenclaw: Repeat with the other house colors.
To make the tiny strips which will be stuck on the scarves, knead the yellow fondant, take a small piece of it and roll it thinly.
Cut four small strips of yellow fondant and stick them onto the Gryffindor scarf.
Make two further red Gryffindor scarves with yellow stripes, then three blue Ravenclaw scarves with grey stripes, three yellow Hufflepuff scarves with black stripes, and three green Slytherin scarves with grey stripes.
Use a tiny amount of water and a very small brush for sticking.