the savvy also rave about french -born maud frizon , known for her fanciful , flirtatious pumps ; london -based manolo blahnik , a specialist in sexy evening mules ; italian andrea pfister , designer of the 1979 `` bird cage '' shoe that spawned millions of plastic imitations , known as `` jellies '' ; robert clergerie and stephane kelian , french designers dedicated to simple , stylish footwear .