Start by hard boiling your eggs.  I made several, but you could of course just make one if that's all you need.  Once cooked, cool in cold water and peel carefully, keeping the egg as intact as possible. With a small sharp knife, cut a slice from one side of the egg to form a flat base.

Take the slice of egg and cut in half. Use a mini circle cutter to form two ear shapes from the pieces of egg, with a flat edge on each one.

With the tip of your knife, cut two semi-circular  slits into the egg where the ears will go.  Trim the ear pieces down to form a thin wedge on the flat edge and slot them both into the slits in the egg.

With the edible marker pens, dot on a nose and two eyes.  Break a piece of uncooked spaghetti into short lengths and push them into the side of the mouse's face to form whiskers.

Finish off with a spaghetti tail if wanted. Please note: The spaghetti is for decorative purposes and should be removed before eating!