Does 'au cheval' mean 'with an egg on top' when translated from French to English?

No, au cheval does not mean "with an egg on top" when translated from French to English. The masculine singular prepositional phrase instead means "horseback," "on horse" or "with horse" whereas à cheval does have the above-mentioned meaning in English. The respective pronunciations will be "o shuh-val" and "a shuh-val" in French.