Taking care not to break the egg yolk, PLACE it in the centre of the hollow in the glass. SHAKE the rest of the ingredients with ice and strain over egg. Instruct drinker to down in one.
This 'pick-me-up' (A.K.A. hangover cure) may be a somewhat daunting prospect irrespective of the present state of your constitution.
Use another spirit such as vodka in place of cognac.