Wilt the spinach by placing in a colander and pouring boiling water over it. Drain the excess water by pressing between two paper towels. Chop thinly with a knife.
Put the ricotta, milk and egg yolks into a bowl and mix well to combine until smooth.
Stir in the flour, baking powder and salt and gently whisk to make a smooth batter.
Beat the egg whites until they become foamy and then fold them into the ricotta mixture.
Add the spinach, salt, lemon juice and zest to the waffle batter, gently stirring to combine.
Turn the Waffle Maker on.
Grease the waffle plates with the butter. When the green light shows, pour a ladle of batter into each slot of the waffle maker. Gently spread the batter into the plates and cook for 6 min. Remove and repeat for the remaining two waffles.
Whilst the waffles are cooking put a saucepan of water on and bring to the boil, turn down to simmer and add the vinegar to the water. Gently break the eggs into the simmering water and cook for approximately 5 minutes. Once the eggs are cooked remove with a slotted spoon ensuring that all water has drained off.
Cut the waffles diagonally in two and place in the centre of each plate.
Top with the smoked salmon and a poached egg.
Place the watercress on the plate along with a dollop of crème fraiche.