Cut one-third from the top of each egg and set aside, then cut a thin sliver from the bottom of each to expose the yolk. Carefully scoop out the yolks and set the whites aside in pairs.
Press the yolks through a nylon sieve into a bowl, add the butter, anchovy essence, a little cayenne pepper and the cream cheese and beat together until smooth.
Spoon the mixture into a piping bag ﬁtted with a small star nozzle. Place a little salad cress in each egg white, then pipe a swirl of the egg yolk mixture on top. Replace the reserved tops, setting them at an angle on top of the yolk mixture, and sprinkle the tops with a little cayenne pepper.
Toss the watercress with the shredded lettuce and the remaining salad cress. Arrange the greens on a serving dish with the sliced radishes and nestle the eggs among the leaves. Whisk together the olive oil with the lemon juice and mustard for the dressing. Spoon over the salad and serve immediately.